Can anybody tell me what I'm looking at?

[duckmeat]

I'm stumped...everybody I've shown it to seems clueless.

retracted

 

[FishBo]

Chalice?

 

[Art13]

cyphastria possibly?

 

[Vinny Kreyling]

feeding tentacles?

 

[Budman422]

diploastrea? hard to tell can you get a pic of it retracted without any feeding tentacles