Mushroom, maybe?

I was curious if there was anyone there who can ID these things in my tank. They look like some sort of mushroom. Several have come off the rock they were initially growing on. Where they had been attached has a hard stony reminder. The ones that have come off are living happily on the bottom of my tank. These can blow up to quite a large size, 5-6 inches across and 1.5 inches "tall", or expell their water and get down to being just 1-1.5 inches across and maybe 1/4 inch tall when fully compressed.One pic is taken under actinic lighting and the other is under white light. These came in as hitchhiers over a year ago and have gotten progressively bigger. They initially came from the rock above where they are currently growing, or at least thats the logical assumption since they rock they are on was a fully dried/bleached out plate coral when it was put in my tank. These didn't show until 6 months after I set up the tank and 2 weeks after I put a new peice of extablish rock above this rock.

 

Sure looks to me like some form of Corallimorpharia, a.k.a. Coral anemones, mushroom anemones or false corals.

Like light, low current.

My guess anyway....:-/

 

Aquarium Invertebrates

 

those look like plate corals

 

Oh yeah, I forgot to add this, when they do shrink down they are rock hard, not firm, but like rocks completely untyielding to touch.

 

My first thought is a mushroom, but It also could be a blastomussa.

 

I agree, look like this: the green plate in front


But than again if you look at the tone at the top right it look like the mushroom's in the photo above only green. When they shrink down are smaller or the almost same size?

 

The large ones are up to about 6" when inflated and about 1.5" hen defleted. In my searching I came up with blastamussa also, but I didn't think those changed sizes like these do. When they are small, not shrunken, but young and small, they can have almost a stalk like appearance occasionally where the body stretched upward rather than outward and it looks like a small flower on a stalk. I'll see if I can get any pics of them in the other states. While thye are looking very green in the pics even the white light pic has some actinic in it. The body when large is pinky beige, and gets greener as they shrink and the chlorophyll gets more dense.

 

Seing how they get so big then shrink down to a much smaller package I would say that they were Corallimorpharia or a type of Mushroom. Nice looking one's at that, wish I had one!

 

where you at? I have 5 that are on the bottom of my tank.