ID help please

[HoppyBunny]

This has grown on some live rock in my tank and I have no idea what it is. This is the only pic I have currently, but there is also a dark purple one on another piece of live rock? Any Idea what it is?

Thanks for your help!

 

[HoppyBunny]

OK, I got one more picture with the "mouths" open. It is about 1/4" x 3/4" and appears to be some sort of filter feeder. It keeps its mouths open the majority of the time, then suddenly it will contract then close the mouths. A few seconds later it will expand to its normal position with open mouths as shown in the picture below.

 

[iamwhatiam52]

looks like a tunicate

 

[Elysia]

I would agree. Usually "things" (small, sessile bags, if you will) that have an incurrent and outcurrent siphon and that can expand and retract are tunicates, sometimes called "sea squirts." They will sometimes appear on live rock even after it has been in your system for a while (perhaps because a new introduction brings in the larvae?) Should be harmless and is just part of the diversity that can crop up in a tank without predators. I think that one is pretty.

 

[noahm]

+1 on Tunicate. I have several of various colors in mine, but the showpiece is this reddish colonial type.

You can see a purple on to the right of it as well.

 

[HoppyBunny]

<a href=showthread.php?s=&postid=14656599#post14656599 target=_blank>Originally posted</a> by noahm
+1 on Tunicate. I have several of various colors in mine, but the showpiece is this reddish colonial type.

You can see a purple on to the right of it as well.

Wow!! Very nice color on those!