Tiny Abalone on Live Rock within Aquarium?

I just purchased some live rock for my aquarium, and I saw some tiny things on it that looked like slugs. On further inspection, I found that they had shells which looked close to abalone shells. Are there any tiny abalones (1/2-1 in.) that can live in the aquarium? Info and meticulousness tips would be much appreciated.
FISH HAVE DISEASE HELP?
Answers:    I haven't had one, but I did find a page on them at one of my favorite marine aquarium websites:

http://wetwebmedia.com/abalones.htm
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