Was checking out my reef tank like I do every evening and saw what looked like a piece of dying coral on some live rock. Looked closer and saw that it was moving. Dang . . . I've got a nudibranch (or maybe some type of slug). Thought it would be so easy to identify . . . I didn't realize how many there are. Any one have any experience with them? What do they eat? Here's some background on my tank. It's been up and running for almost 2 years. I've got live rock, inverts, fish, etc. Evidently he (or she) hitch-hiked in on some live rock or coral. I haven't added any live rock or corals to the tank in about 3-4 months. Everything I've read says that nudibranchs are short-lived and will probably starve in an aquarium. That may be so, but this thing had to come from somewhere and she's definitely been in the tank for a while. She doesn't look like she's starving to me. So what is she eating??? As the image shows, she's white with small bumpy protrusions. She's about 2-3" long and maybe 1/2-3/4" of an inch wide. Any help or advice would be greatly appreciated. Thanks.