As some of my Facebook friends know, I now have a saltwater tank. A few days ago it was still freshwater but then I decided to get a saltwater after seeing a whole setup at work for $80 (it was a 12 gallon with everything but the rock and fish) but then I couldnt think of where I would put it or anything. So since I work at a petstore I started asking questions about saltwater and found out its pretty easy when it comes down to it. I had 2 29 gallon tanks, one with firemouth cichlids and their babies plus bushynose pleco pairs and a marmokreb crayfish and tons of snails. The other tank had some dwarf gouramis, guppies, kuhli's, and some other stuff, nothing I was too attached to. I decided to turn the second tank into a salt water tank so I sold the fish to the store and started that night. I got the live sand first from a coworker and some dirty water to get it going. Then the next night I bought some liverock and the salt to make the rest of the water and got that done Saturday night. The guy at work said it should be ready to add fish today so I bought an anemone, a firefish, feather duster, and a coral banded shrimp. Then went and got a neon goby and 2 classic clownfish (forgot the technical subspecies name, not the tomato, maroon, or clarkii but the other one). They are all doing great but here is my question. The live rock came from a tank that has been set up for like 20 years, the guy tore down his tank so sold it to the store with tons of other stuff. The liverock looks awesome, its covered with glass anemones, zoanthids, mini feather dusters, and some other cool stuff. Well tonight I was watching the tank and saw something that looked like a slug, it had little prickly looking things on the side, then it went back into the rock. Then about an hour later I saw another, it stretched out about 8" and was eating the pellet food on the bottom. Then more came out, all of them larger and creepy looking. So if anyone has a saltwater tank and knows what they could be, can you tell me? Will they eat fish? If anyone has any advice for me I would appreciate it.