anemone ?

just a WAG (wild ass guess) but they will probably die from lack of
light.
kc

Could be but the Chesipeake bay has very very bad visibility to begin
with. Would colour have something to do with photosynthasis? Like I
said they are very dark brown/black in colour. They almost look like a
urchin but on a base like a normal anemone. The tank they are in now is
better lit than the waters they came from.

Vicki

My domino damsel has decided to host the small patch of barnacles which
I saved too. Looks kind of cute.