white worms in salt water aquarium

Question
Last night my husband and I were watching tv when we knowticed tiny white worm looking things in our 55 gallon aquarium, they seemed to multiply very fast and seem to swarm the tank.  I fell asleep but my husband said that they over about an hr or so turned brown and died.  I was wondering what they are, if they are harmful, what caused it and how can we prevent it from happening again.  Thank you

Answer
Not sure but go to about.com and click on hobbies and games. Next page click on saltwater aquariums [lower left. You will be at a site run by the Hauters, and you will find almost any saltwater answer you can imagine. Sounds like a copepod bloom. Have you added any new live rock to the tank? Gerry.