Honestly I'm freaked out!

But curious!

The new live rock I brought home yesterday is moving, it opens up and then snaps shut. I'm thinking maybe a clam, but I have no idea. I posted a video on YouTube, sorry it's such a long video, but of course as soon as I started taping it, it stopped moving. If you skip about halfway it starts moving a lot.

New Hitchhiker! - YouTube

 

Man, that's knarly... I honestly don't know what that is....

 

It's either a bi-valve (Clam) or a Tunicate. If bi-valve it looks like it's rock boring and upside down.

 

Is it good or bad?

 

It would not concern me. A cool hitch-hiker but harmless. If you just added this piece and it's newly acquired and not cured you may see some die off. The only concern I would have is if this was a small tank, you might see an ammonia spike.

 

Ok, it's a 55g so I'll keep an eye on my levels thank you!

You said it looked like it was rock boring and upside down, should I try to flip it over, or move it down to my sand bed?

 

No I would just leave it be. It's really hard to be sure because of the angel it's at.

 

I'll charge up my waterproof camera and see if I can get a better shot at it. I looked up pictures of bi-valve clams, and it doesn't really look like one its almost shaped like a snakes head with two v shaped grooves running down to a point.

 

I will wait for an update. I looked again and can not come up with any other ID, could be Oyster too. Is it attached to the rock? Touch it and see if it's hard or leathery.

 

its rock solid, I couldn't move it if I tried