they came out of the rockwork probably. if you're really bent on getting them out, you can buy a trap for too much $ or make your own. there're plenty of instructions out there on the net on how to do it. a couple LFS I visited (B&B and planet fish) don't sell them just because they're so simple to make. Toni at pfish suggested a glass coke bottle in your tank with a bit of brine shrimp at the bottom. angle the neck of the bottle so the lip is on the rockwork where you think the worms are. they'll climb in but not out supposedly.