the first one i ever saw was like that.it was eating something then it sprayed that "stuff" everywhere.i could not figure out what it was.then shortly after i lost some soft coral.so i decided that thing killed it.the next time i saw it i got rid of it.that was months ago.since i have seen one or two here or there.then last night there were literally hundreds of them.all different sizes.its crazy because i work nights and look at my tank every night when i get home to make sure all is good.last night is the first time i saw them like this.i would guess its a good sign.like pods maybe.a sign of a maturing tank