No clue what this is...

[Msmith88]

Got a new piece of live rock the other day and just found this laying next to it on the sand. Never seen anything like it... Anyone know what it is or if it's safe for my seahorse tank. It's just a solid disk shell, haven't seen anything moving out of it, or even an opening for that matter

 

[Flreefer]

Looks like the cap that snails have to seal off their shell. Basically part of a snail skeleton...harmless to your tank.

 

[Msmith88]

Your right it does, just seemed pretty thick...

 

[Wendy8184]

+ 1 snail part...have many a dead snail part in my tank

 

[Rosesrblu1]

Looks about the size of a Mexican turbo snail. Check if your shells are missing one of them. You can leave it take it out. Won't harm the tank, as the only the fleshy part of the snail will foul the water.

 

[Msmith88]

I think it came in on the live rock because I've never had a snail that big in the tank. I do want to get one though