maggot kind of craetures floating or swimming through space/water



I've a question about a movie I've once seen, but forget what the name is and the total plot of the movie.

I remember big maggot kind of creatures with sharp teeth floating through space or swimming in water and its attracted to things that move. It looks like they are hunting and you'd need to move real slowly to pass them so you wont be eaten. Who can help me remembering the title of this movie ?

Regards, Peter