What is this creature?

[maryc137]

Yesterday morning I was looking at my tank with a flashlight before going to work. I saw something that looked kind of like a brown slug. It was about 1/2 inch in diameter and maybe 1 inch long.Could have been longer because it was going behind a rock so I'm not sure I was seeing the end. It moved just a little bit, otherwise I would have thought it was a little hunk of broken off rock or something. Anybody know what it is? Can't see it this morning. I've named him Bob the Blob

 

[cyn]

Do a search on sea slugs or nudibranches. It sounds like possibly one or the other.
Try this link: <a href="http://www.bunaken.fsnet.co.uk/sss-sea-slugs.htm" target="_blank">http://www.bunaken.fsnet.co.uk/sss-sea-slugs.htm</a>
HTH,
cyn