Shell picking from Red Sea sand

[Hobbyst46]

Does digging deeper into a beach sand bank offer ancient forams?

Hi Charlie,
foraminifera can be used to research the movement of coast lines. When you bore a hole with a hollow drill you can part it in layers, clean it ( I think with H2O2) and look whether and which foraminifera are there.
Our microscopy group has a small offspring that works on micro palaeontology, mainly foraminfera. They once got drill cores from the river Elbe in Hamburg and made a profile of the foraminifera in the different layers. This might be very interesting, especially with the raising water levels today.

Bob

The river bed is composed of sand layers that accumulate due to the erosion of rocks upstream. I guess that fossils are found in much greater depths. And on land, in exposed rock layers, like those in quarries, caves, canyons, craters etc.

[75RR]

A little more info:

OIL EXPLORATION
Foraminifera are used to find petroleum
Some species are geologically short-lived and some forms are only found in specific environments. Therefore, a paleontologist can examine the specimens in a small rock sample like those recovered during the drilling of oil wells and determine the geologic age and environment when the rock formed. As a result, since the 1920's the oil industry has been an important employer of paleontologists who specialize in these microscopic fossils. Stratigraphic control using foraminifera is so precise that these fossils are even used to direct sideways drilling within an oil-bearing horizon to increase well productivity.

https://ucmp.berkeley.edu/fosrec/Wetmore.html

[MicroBob]

are even used to direct sideways drilling

Hi 75RR,
25 years ago I applied for a job in a copmany producing drilling equipment. At this point of time they communicated with the drilling head by means of pressure pulses in the water supply to the head. It's fascinating to hear that foraminifera are so specific to steer the head on such a small scale! In other areas of science one would wish to have such detailed information.

Bob

[Hobbyst46]

My hunt goes on.

First, on behalf of motivating suggestions (by zzffnn, MicroBob) to try more diffuse and even illumination,

May I suggest use an objective hood (wrapped tightly around objective lens) made of Vellum paper for better difdusion? Even think office paper will work better than not having any diffusion.

I managed to quickly assemble a crude LED ring for diffuse illumination from above the slide, not really epi- but radial and oblique, so to speak. It is a flexible self-adhesive LED strip inside a cylindrical ring. About 15 warm-white LEDs along a perimeter of 14cm, total of 1.5-2W (guess). The LED current is 25mA. Concentric with the LED strip, I placed an inner ring made from a white thin filter cloth (13 um mesh size), to diffuse the light. This cloth is an efficient diffuser. The objective front end is thus surrounded by the illuminator diffuser, at a small distance. A heat sink is a must, and I used very crude patterned 6mm scrap aluminum plate for it. The plate is attached to the round ring with 4 small screws. I ordered thermal cement for better heat conduction. It is not a truely effective heat sink, but for short observations - OK.
The illuminator is first placed on top of the slide, then the objective is lowered with the coarse focusing knob. Naturally, the specimens are just for the 2.5X..16X objectives. It is not possible to switch objectives without lifting the objective so it is out and above the ring.
Photos 24 and 25 display the bottom and top side of the LED ring illuminator.

Hopefully later on I will compare it with the two-LED non-diffuse top light.

More fun was finding a tiny (0.3mm) strange form among the sand grains. I picked out several identical such things, that look like an assymetric cap, and a rounded tip. It resembled a clam-shell, but of this size ? it is semi-transparent, faint brown color, ornamented with contours (layer bounds).

I baked it for an hour at 220C, but nothing changed, so it is made of mineral, not organic. Then tried polarization microscopy, and it shows birefringence, so I thought it is a calcite skeleton. The marine biologist Dr. Shai Oron suggests that it is most probably Bivalvia larva. Made of aragonite and possibly an outer thin calcite coating. The composition depends of the developmental stage of the larva.
Photo 26 shows it under the top oblique light (10x0.30 Neofluar, not phase contrast objective), photos 27 and 28 under phase 3 +POL (two different rotation angles), using the same objective. I tweaked the field aperture for maximum effect in the latter case.

[MichaelG.]

That little Bivalvia is a lovely subject ... Well found, and nicely imaged.

MichaelG.

[Hobbyst46]

Thanks, MichaelG !
I have been told that such larva are caught in plankton nets. But mine were buried in the intertidal sand.

[KurtM]

That tiny shell is beautiful, looks to be a ton of potential in it for a truly spectacular image - not that the ones you posted aren't very nice, just looks like a grand subject to play around with if it's your thing. Be really great if some size context could be added to show just how tiny it is, like the eye of a needle or some such. Just thinking out loud.

[Hobbyst46]

That tiny shell is beautiful, looks to be a ton of potential in it for a truly spectacular image - not that the ones you posted aren't very nice, just looks like a grand subject to play around with if it's your thing. Be really great if some size context could be added to show just how tiny it is, like the eye of a needle or some such. Just thinking out loud.

Hi KurtM, I am a documenter rather than photographer. Will try to find some more of these tiny shells in the sand pile.

Since they are quite rare, I spread the sand in a 50mm diameter petri dish, to form a monolayer. With the stereoscope, under simultaneous epi-illumination (white light LED ring) and trans-illumination (warm white LED). This gives a good combination of contrast, color rendering and differentiation between the opaque and transparent sand grains. Sifting with a dry wooden toothpick. The shells are very fragile so, instead of twizzers, I pick them up with the wetted tip of the toothpick.

Sending a PM.

[Hobbyst46]

Very nice images, Hobbyst46!

May I suggest use an objective hood (wrapped tightly around objective lens) made of Vellum paper for better difdusion? Even think office paper will work better than not having any diffusion.

In you photo #19, I can see two hot spots, perpendicular to them, I can kind of see two darker areas too. If diffusion takes away too much light, I would suggest adding 1-2 more LEDs. Or simply use those tiny Maglite Solitaire LED flashlights (powered by AAA batteries).

Better still, use a half ping pong ball (drill a hole for objective to see through) and 2-3 speedlites. Charles Krebs uses that kind of set-up and produced many award-winning microphotographs.

In US, one can also buy miniature "beer pong" balls about half the size of a regular ping pong ball. I bought some from my local Kroger (located at Autumn Creek Village, Texas 77546, in case Kurt wants to buy them). Smaller diffusion ball that matches subject size exactly will provide more even diffusion and save working distance.

So, I adopted the idea of diffuse light, and considered yours and MicroBobs ideas. The simplest of all, for me, was the objective hood plus enhanced intensity of the light. So I quickly made the LED ring shown in photos above. It is composed of 15 LEDs on the inside of a cylindrical ring, diameter 45mm, ~2-3 Watts altogether. A 6mm aluminum plate heatsink helps somewhat to prevent over-heating, although only for very , short sessions. The objective hood is wrapped around the objective, concentric with the LED ring. It rests freely and is supported in vertical position by the objective. The hood is made of a 13 um mesh nylon filter cloth (sort of a very dense "cheese cloth"; bought a 1sqm of it that lasts forever).

Indeed, diffusion is effective. The "harsh" reflections are gone. I verified that these reflections arise from the Foraminifera surface and not from the cover-slip. The forams are mounted on glass with glue, but only their hidden bottom side touches the slide, and they are completely dry, not wet.
So, here are two photos of the "zebra" (as KurtM nicknamed it). No 21 is the previous one, illuminated withought diffusion. No 29 is the recent one, created with the LED ring plus hood. Both photos have been tweaked a little, hopefully to achieve the same color, hue, contrast etc.

Neither is contester, yet I personally like them both...
Comments are welcome.

[KurtM]

Please do be aware that not all harsh reflections are bad. In macro and extreme macro it's certainly a major challenge to avoid blown out highlights, and much has been written and discussed on the subject, but we must be careful to remember that occasionally, even if only very occasionally, harsh reflected light can actually help define a subject when handled carefully. The 'zebra foram' just shown looks like a good candidate for such surface highlights. Keeping reflections under control so that they become an asset and not a detriment would be the sort of challenge I happen to get into. Not that I'm always successful, but I do enjoy this sort of challenge.

[zzffnn]

Very nice work, Hobbyst46.

Sorry, I did not mean your light in 1st attempt was harsh (and I apologize, as my previous post was too blunt). I do prefer your image #29 though.

Sometimes hot spots are trade-offs that we have to accept, for convenience, working distance or speed. And indeed, if one removes all specular highlights, image may be boring (for example, check out those field macro images shot with fully crossed polarizers, many of which look dull).

[75RR]

Given that you are a documenter rather than a photographer and as both images show the shell to advantage, I would go with the 'simpler' option - whichever that might be.

The idea of a scale is a good one, and though a needle for comparison has a dramatic flair it turns out there are many sizes so I do not think that in documentation terms it would work that well.

Took the liberty of fiddling with the images. Have not seen the originals through the eyepieces of course ...

Removed a little yellow cast and added a little contrast.

[Hobbyst46]

Very nice work, Hobbyst46.

Sorry, I did not mean your light in 1st attempt was harsh (and I apologize, as my previous post was too blunt). I do prefer your image #29 though.

Sometimes hot spots are trade-offs that we have to accept, for convenience, working distance or speed. And indeed, if one removes all specular highlights, image may be boring (for example, check out those field macro images shot with fully crossed polarizers, many of which look dull).

Hi, zzffnn! thanks for this response and again for the previous response ! both are welcome - motivating, and pour light on the subject (pun) from different perspectives (more pun). The trick of objective hood diffuser is cool !

[Hobbyst46]

...The idea of a scale is a good one, and though a needle for comparison has a dramatic flair it turns out there are many sizes so I do not think that in documentation terms it would work that well.
Took the liberty of fiddling with the images. Have not seen the originals through the eyepieces of course ...
Removed a little yellow cast and added a little contrast.

Thanks 75RR, in fact the "fiddling" made them more similar to the original view through the eyepieces (just verified that) !. Which parameter did you adjust to remove the yellow cast ? I am not using photoshop but most parameters are common to all software.

[75RR]

Glad you found it helpful

Steps taken:

I fiddled with Hue/Saturation:
Chose Yellow under the Master drop down menu, then used the dropper on the area I wanted to work on.
The next step is to drag the Saturation slider to the left (minus symbol)
The more you drag the more colour you eliminate.

I also fiddled with the Curves a bit, using an ‘S’ pattern

[Hobbyst46]

Glad you found it helpful

Steps taken:

I fiddled with Hue/Saturation:
Chose Yellow under the Master drop down menu, then used the dropper on the area I wanted to work on.
The next step is to drag the Saturation slider to the left (minus symbol)
The more you drag the more colour you eliminate.

I also fiddled with the Curves a bit, using an ‘S’ pattern

Thanks a lot. I find that I can achieve a similar result with Microsoft Office Picture Manager.