Can you ID this ?

December 29, 2000
From: Chris Stephens


I received some live rock with a mysterious slug type hitch hiker and I wonder if you could id it. There are two of them, one much larger than the other.

Amazingly they survived the journey and are currently in a breeding trap in a sump tank.
Many thanks,

Stephens, C., 2000 (Dec 29) Can you ID this ?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Chris,
I think this fits more into the 'worm' category rather than 'slug' category but as I've looked at your photo I'll add it to the Forum for reference.

It is a Peanut Worm or sipunculid worm, which are a small group of worm-shaped invertebrates in the Phylum Sipuncula. They are called peanut worms because that's what they usually look like. Only when they are feeding or disturbed does the long tubular 'introvert' which is on the right of your photo, unfold from the body cavity. Any good invertebrate book will give you more information on these animals. As far as molluscs are concerned they are the sole food of most species of the predatory snail family Mitridae.
Bill Rudman.

Rudman, W.B., 2000 (Dec 29). Comment on Can you ID this ? by Chris Stephens. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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