Which one of the following pairs is mismatched?

Pearl is obtained from Pinctada vulgaris. Related Theory Pinctada (pearl oyster) belongs to phylum Mollusc. It is bilaterally symmetrical, triploblastic and coelomate animal. Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and visceral hump. A soft and spongy layer of skin forms a mantle over the visceral hump, the space between the hump and the mantle is called the mantle cavity in which feather like gills are present. The anterior head region has sensory tentacles and the mouth contains a file-like rasping organ for feeding, called radula. They are usually dioecious and oviparous with indirect development.