Last night while feeding my wrasse, I noticed a little guy, about 2-3 inches long, hanging out in the cave I made of Live Rock. He was dark, like black, with 3 or 4 white stripes running the length of his body. He has a rectangular head that slopes towards his snout, round fins behind his head, and a fan-like tail fin. He hasn't left the cave, and when he sees me he darts into deeper hiding (that's the reason I haven't been able to get a pic). He seems to stay in one place (until he sees me), rather than swim around, if that helps. And he must have survived a 40 minute car ride in the live rock, with probably no water (unless there was a pocket of water in the rock).
In my 46 gallon tank right now is 6 mexican red legs, 2 hermits, a wrasse, a cleaner shrimp, and 2 softies. I have 40 lbs of live sand, and about 30 lbs of live rock. My params are 79-81 degrees, s.g. 1.022, Ammonia ~ 0, Nitrate ~ 0, and Nitrite ~ 0. The tank is new, about 3 weeks old. I have a canister filter and a coralife 20000k light.
I really would like to know if I can lure him out somehow, for a pic, or if someone would know what he is...