Is this a mushroom?

[Jonas Bergkvist]

The orangea one with holes in it. Seen at my LFS. And it looks really beautiful. I would appreciate if anyone could tell me what it is thank you!

 

[Goaway]

Looks like a type of colonial tunicate.

Edit: i should say, amazing filter feeder, can and will smother some corals. So, best left in its own territory.

 

[dbowman5]

War on marine invaders seems a losing battle

On a cool Friday morning last month, a dozen curious Rhode Islanders lay down on the pier at Point Judith Marina to collect so...

narwhalslefttooth.blogspot.com

this looks like it. it is an invasive species possibly found and collected by aquarists