Snorkeler's Cube

Thursday as I was doing a quick water change I found a tentacled creature sitting on top of my first sump baffle glass.... looked like an aiptasia to me so I tried to suck it with the hose. It receded into the baffle and I lost it.

A few minutes later I saw it drifting submersed in the water on the other side of the baffles, close to the return pumps, stout and tentacles all spread open, like a spider. This time I took it out with plastic claws (didn't want to touch it).
...