parasite?

[lowlife]

i just noticed a few really really small worms less then a 1/4 inch. They were in my sand and one behind a snail on the glass almost looks like hes eating the snail. They look like centipedes with two long hairs coming out the top, and green in color. They're to small to get a decent pic of, but does anyone know if theyre good or bad, will they eat my corals?
any help would b great
thanks

 

[krux]

do a search for bristle worms. they are detrivores, generally cleaning up any dead matter that floats to the bottom. once that has been consumed they will work on uneaten fish food.
their population is limited by food sources, so if they go up in number, something may be amiss.
6 line wrasses can sometimes help control them if you choose to rid yourself of it.