Flat-shelled snail type things.....

[Casey]

I've got at least three of these creatures in my 30 gallon. They came in with live rock. They appear to be some sort of snail, but don't have the typical round/spiral shell. All three are about a 1/2 inch long with a pinkish-purplish almost flat "shell". They cruise around the live rock, sand and on the glass sucking as they go. Anyone know what they are and if they're OK to have in the tank.

In the picture one of these guys is to the lower left of the hermit.

[matrixnyc]

Does it have any legs? In the photo it seems to have legs.

[phistio]

looks like a chiton to me...

[matrixnyc]

Chiton: Rounded upper surface, flattened lower surface. Upper: Eight calcareous plates fit into one another, girdle surrounds the calcareous plates. Lower: Oval muscular foot. Mantle cavity is in between .

http://www.reefs.org/hhfaq/img/faq_chiton.jpg

[Pineapple House]

I disagree. It doesn't really look like a chinton. Chintons will have a harder based shell completely surrounding the inside critter, in the picture this has a smooth round shell covering it half way.

This is most likely a Stomatella varia. It is a small reef-safe herbivore. A nice grazer that will reproduce readily and will consume diatoms with gusto. They're completely harmless grazers. Heres a pic:
http://www.reefs.org/hhfaq/img/stomatella.jpg

It looks just like the one shown in the above pic. Phistio, and matrixnyc, are you talking about the hermit above?

PH =)

[phistio]

no...i was referring to the critter to the bottom left of the hermit...i thought it looked like a coraline encrusted chiton, though it could be a stomatella varia.

[Casey]

Thanks for the input, everyone. I think this picture is better. Critter is pictured in the center.

[phistio]

ok...convinced it's a stomatella...before i saw no "snail foot"...now it looks pretty apparent.

[RazerCorals]

I agree with Pineapple. I have tons of those in my 40. They do a super clean up job ans reproduce like mad! Every morning b4 my lights turn on I count between 60-70 just on m glass. And for everyone you see there are usually about 9 more you don't see. They also don't have a heavy shell so they can move pretty quick.

[Marco]

New to this board but definately not new to Reefing. What you have is Stomatella ditto on the multiplying rapidly. They will find a high spot on your rock and start "smoking " is what I like to call it but they are releasing eggs. Excellent hitchhikers. I had some peppermint shrimp wipe out my population in my 10gal. Nano at work but after the shrimp were removed they started to show up a couple of months later they were real tiny. Just my .02

[killroysrevenge]

I have these also. I did not know what they were but I knew they were nocturnal algae grazers that are afraid of their own shadow. I started with none and now I have 15 or so. My astea snails seem to do better though.