Slug? on live rock

January 9, 2004
From: Manuel Marquez

Dear Bill
I have noticed a very weird Slug on my live rock, the rock could be from north West Australia. The slug moves in a very slow motion about 10mm per hour, it is heavy and very flat. Here is the pic.
Are you able to tell me what he is and what he eats. Is he OK in a smal reef tank.
thank you
Manuel Marquez

Marquez, M., 2004 (Jan 9) Slug? on live rock. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Manuel,
Your 'slug' isn't a slug. It is a chiton. Have a look at the chiton Fact Sheet for some background information. Chitons are a distinct group [Class] of molluscs which have 8 shell plates which form a protective 'coat of armour' over the body - much like in an armadillo. You can see some of the shell plates in your photo. A chiton or two in an aquarium can do no harm and probably is a useful way to scrape algal film off the glass
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jan 9). Comment on Slug? on live rock by Manuel Marquez. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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