Name that Invert :) ...In six notes or less: Chiton   5/23/07 Hi Crew <Hi Jackie, Mich here!> I was hoping you could help me identify this invert that I purchased.   <Better to ID first then purchase.> I am very new to reef keeping and have been researching every animal that I have.  This one, I cannot find anywhere.  It seems kind of like an abalone in that it has 4 small holes on top of its back. <Hmm, Chitons typically have eight.>   However, it does not have a shell.  More like a leathery smooth back.  I am enclosing a pic, but I apologize it isn't very good.  This is what I have observed.  It is nocturnal.  It is grayish, brownish, green colored with dark brown stripes around it on the fringe/feathery area (cerata?) below the mantle but above the foot.  Its shape is oblong with perhaps a bit of a point on its rear end.  It has two rhinophores (striated bulbs I think).  It spends almost all of its time on the live rock, but sometimes ventures to the glass, stays low in the tank anyway.  I have not seen it on the substrate ever.  It can retract its head into its mantle - when it is resting or frightened it pulls itself into the mantle and appears more circular/oval in shape.  It can be somewhat flat (1/8th inch perhaps), but have noted a few instances where the foot/ underside seems to almost inflate such that it doubles in width.  I have trouble thinking it is a Nudibranch since all that I have seen suggest they are quite colorful - this invert is almost hard to see when it's on the rocks.  It doesn't seem to have a shell even though its top is smooth and seems thickish.  Nothing else in the tank bothers it.  For the longest time it seemed to spend all its day time resting in the crevice/cave that my Daum reef lobster hangs out in during the day -  oddly, since the lobster is very possessive of it's lair and nothing else seems to be able to even approach it without getting snapped at.  It seems to feed off the rocks/glass and I have not seen it bother any snails or my crab or clowns.  It rests upside down almost exclusively.  It is about two inches long and about half inch across, eighth inch width I guess.  So I hope this helps you to help me find out what this creature is.   <I believe you have a Chiton, though a limpet might also be a possibility, but I'm leaning toward a Chiton.  More here: http://www.wetwebmedia.com/chitonfaqs.htm > What is its diet?   <Chitons are herbivores.> Where does it come from? <Chitons are found in all seas.> I tried to find out more from where I got it at the pet store but I am now doubtful of the knowledge of the staff there since they also sold me a sand sifting tiger star and I have neither the substrate depth or tank size to sustain it (I am going to try to exchange it).   <It is always best to do your own research before making any purchases.  Unfortunately, sand sifting stars typically starve to death in captivity.> My tank is 20 gallons.  I have about 10 pounds live rock.  Aragonite substrate about 1.5 inches.  Rio Nano Protein Skimmer.  Aquaclear hang on filter with foam and carbon inserts.  Elite hush hang on filter with BioMax in place of cartridge.  T5 Glo Daylight and Actinic lighting.  Tank occupants are Red Mithrax Emerald Crab, Green Bubble Tip Anemone, <Mmm, I personally am not a big anemone fan.  They like to go for walks at the most inopportune time, which can spell disaster, especially in such a small system.> Daum's Reef Lobster (purple), <Should be in a larger tank, closer to 50 gallons.> Two false Percula, Sand Sifting Star, 3 Star Snails and one bumble bee snail that is currently missing in action.  Water parameters are all good.   <Vague.> Using RO. <Good.> Salinity is 1.026.  Temp is 80.  Thanks for your help. <Welcome!  Please do get in the habit of researching prior to purchasing.  Mich> Jackie