i saw this at that fish place today when i was there and it is the coolest little thing............it was sucks the reef sand in its mouth and spitting it out its gills..............it looks like a goobie but i have never seen it
also know as a golden head goby. I don't recommend it to anyone. they are very active sand sifters and don't take to other food very well. my friend had his sand decimated in a few weeks and then the fish starved. you want 200-300 gallons with a deep sand bed.
there are so many critters that are available in the trade that just will either not survive or decimate things in our tanks. it is so much more important to research, like you did, before any purchases.
That little guy will make your tank look like there was a snow storm pass by. Unless you have lots of time to stand by your tank and blow sand off the rocks and corals with a turkey baster, I don't recommend one, even though they are cute.