Kefir is a fermented milk drink and healthy food. It is a bit like thin yogurt. It can be made by adding Kefir grains to milk and then letting it ferment overnight. The Kefir grains contain bacteria and yeasts that convert the lactose (milk sugar) in the milk to lactic acid. Kefir is made in many countries around the world, and especially popular in the Caucasus region and Russia. It spread also to other countries where it also became popular.
I put both the Kefir grains as well as some of the liquid under the microscope. The Kefir bacteria were initially difficult to see, so I used Phase Contrast microscopy to make them more visible.