Just setup the tank a few days ago. Have a few hitchhikers popping up. This one's ID eludes me. At first I thought flatworm when I saw one on the glass. But seeing them on the rock they have more of a grub shape. They are 1/4" long, white-gray with a gray stripe along the side. No protuberaces (ie. antennae, siphon). They have no shell that I can see, however, each has what looks like a small bundle of rock or algae on its back. This is the best pic I could get. Thanks in advance.
Update. I touched one and it has a hard smooth, rounded shell but seems to be covered by it's mantle. The rock/algae was exactly that. It fell off once I touched it. Baby Cowrie's maybe?
+1 on Stomatella Varia. I had one that rode in on my LR and now, 4 months later, I have about 8 of the little buggers. They seem to move fast and eat slow!! Very beneficial to my system!!