And where there's two...

I always called these "ninja turtles", cuz they have that tiny little shell on the back - like Donatello and the boys.

I had a limpet come in to my tank as a stow away. Started out about 1/2" long. I thought it was cute then. Now, it's well over an inch long, and it knocks everything over in its travels - like those big Mexican turbos. Still, I won't get rid of him, unless I find myself with an excess of garlic butter one day...