Coral Meerslug

The Coral Meerslug is a fully aquatic, slithering creature found in Pikmin Z. It is a legless, slug-like animal found underwater with a rocky covering on its back to mimic coral. These colors vary from yellow, to blue, to green, to red.

Biology
The Coral Meerslug was once a species on land until it slithered back into the sea. It holds little threat to the party.

Piklopedia entry

 * "The Coral Meerslug is the sole species of slug-like invertebrate that has fully adapted to life in the sea. Its back has hardened up to mimic the coral it inhabits itself in."

Strategy
Hardly required, as one throw of a Blue Pikmin easily disposes of one.