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(phylum Mollusca)

Class of elongate, bilaterally symmetrical, marine molluscs, first appearing in the Upper Cambrian, in which the shell, if present, consists of seven or eight overlapping, calcareous plates on the dorsal surface. The class comprises the Polyplacophora (chitons), and the Aplacophora which have no fossil record.

Subjects: Zoology and Animal Sciences — Earth Sciences and Geography.

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