critter/coral ID's needed please?

[expatgoalie]

Hello all,

My tank has been up and running for about 4 months now and I've been putting pieces in as I find them slowly. With that, however, I have a couple of mysteries that I would love some help from the brighter minds here to identify.

First, a FTS for any interested-

Now, my questions

1) I bought this piece as 'zoas on a rock'. What kind of zoas are they? They're growing great, but I was just curious.

2) This 'rock' is not really a rock. there is an invertebrate of some sort as part of it, I am convinced. I was watching the tank feed a few weeks ago when I noticed the zoa rock would rock up (shell opening), then slam shut really quick (closing). The think opens up ~.5", but its location in the tank make it so that I cannot see inside the shell very well. I can only see what looks to me like a fleshy cover to the opening with two large (breather) holes? See pics to sort of explain?

You can sort of see what I am talking about here. It doesn't look like a clam, but it is absolutely alive, and I have no idea if it's good, bad, indifferent, or what to do really.

Finally, #3) I have some very small pockets of this bubbly algae growing. Maybe 3-4 locations, all smaller than a dime in area. What is it, and should I be alarmed?

Thanks for any and all help.
Paul

 

[fitch4]

#1
Green zoas, lots of people name them but they are really all the same species with different color patterns. I am sure they have a "name" and you could check ZoaID if you want the "accepted name"
#2
Maybe a clam of some sort. Quick shutting of the shell sounds like a clam or scallop of some sort.
#3
It is bubble algae, probably Valonia or some related genus. Alarmed? No. It will spread in the tank and can be a nusiance. Best idea is to pull the rock out and pick off the bubbles as carefully as you can, trying not to break them in the process.