Hydra-like Cnidarian from marine sample -- what is it?

[macnmotion]

While wandering through my marine sample (Gulf of Thailand), I came across what I first thought was Hydra, however Hydra don't live in marine environments. I'm trying to figure out what this is.

Here are a few looks in a video, and also a quick image stack of the tentacles.

hydra stack 3 sm.jpg (105.78 KiB) Viewed 836 times