The polyplacophorans, commonly known as chitons, are often considered by scientists to be the most primitive of all existing molluscs. Strictly marine, the majority of the chiton species inhabit rocky seashore environments where their low dome-shaped shells are well suited to withstanding the violent serge of ocean waves. They all cling tenaciously to the hard substratum and if dislodged from its rock, will roll up into a ball to protect their fleshy under surface. This also allows it to roll around safely in the waves until it can reattach itself to a rock. Most chitons are herbivorous; however a few are predatory. They are nocturnal in behavior.
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