Scary looking thing in my live rock

I have a three year established reef tank that I took in from a friend that couldn't afford the hobby anymore. I was looking over the tank and saw this monster looking thing with its mouth open living in the rock. I shined my flashlight at it and it shut its mouth. I tried to get it out with a pair of tweezers, but no luck. Please help me identify it, if I should get it out of my tank, and how can i take it out. Scares the crap out of me if eats one of my tiny fish or inverts. Thank you for any response, and good day!

 

Does it try going back in the hole? To me from what I can tell, it looks like a clam of sort. Kinda hard to see pic

 

I have to agree with Bob. Too hard to tell.

Maybe a scallop? I have a hitch hiker on the base of my scolly that is a scallop.

If you can take a video of it and post that via youtube and show what it does? That may help. If you didnt say that there was something there, I would have thought that it was part of the rock.

 

It's a rock boring bi-valve of some sort. Harmless filter feeder. I've had a few in rock that came from the Keys.

https://www.google.com/url?sa=t&rct...apb2KjFbw0oCN10Xv8cDPAg&bvm=bv.43828540,d.aWc

 

Makes total sense. These live rock are from Florida. I watched a neon goby sit on it and luckily the "filter feeder" did not eat it. Thanks for your help!