Clam looking thing?

[drummerboy]

Ok, this is going to sound like the weirdest description every, but it's one of the wierdest things I've yet to see in my tank. In a crevice of my live rock there is a brown (looked like a crab at first) thing with a scalloped opening facing the top of the tank. Out of this scalloped opening is white stuff sticking out (looks like a filter feeder, it sticks it out and pulls it in periodically). So, I thought I had a clam of sorts, but when I shined the flashlight in for a closer look, the thing backed in to the crevice pretty darn quick (don't think clams move like that). Any ideas? Haven't found anything about them on hitch hiker sites, and it doesn't look like a shrimp or crab that I've ever seen. Sorry for the long desctiption, but does anyone have any ideas? It's about 3/4 of an inch around (at least as much as I've seen).

 

[lordofthereef]

might be a mussle. i have tons of those things in my tanks.

 

[drummerboy]

I'm guessing since you have quite a few that they're not harmful to your tank. I'm just wondering since I know where it is right now, I think I can get to it with a pair of tweezers. Should I pull it out while I can still see it? I just don't want it to end up being like a mantis shrip or something, and I missed it when I had the chance.

 

[fishymissy]

It could be a barnacle.
Is this it?
<a href="http://www.umassd.edu/Public/People/Kamaral/thesis/Barnacles.html" target="_blank">www.umassd.edu/Public/People/Kamaral/thesis/Barnacles.html</a>

 

[drummerboy]

The second picture does look a little bit like it. I still find it hard to believe that it'd be so mobile though. If I do decide to switch to a sand bed today, it's gonna get pulled out of it's home when I take the live rock out.

 

[drummerboy]

Can't afford a digital camera along with this hobby , so no pic I'm afraid. Yeah, it has to have some way to sense light, and I would think with the way it moves that it has to have legs, but I can't see either. I've decided to switch from cc to sand though, so I'm going to yank it out of the rock to look at it later.