Just found this just don't know what it is.

[newguyintown81]

So I just got some live rock and looked over and this was climbing on my glass this is a new tank.

 

[SandJ]

Looks like a chiton (if it looks like a slug with a fingernail on its back it is a stomatella snail though). Good part of the clean up crew.

 

[KJ]

So I just got some live rock and looked over and this was climbing on my glass this is a new tank.

Isopod Serolid.