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Squids’ Shells: From Armor, to Vehicle, to Ghost

Shells made their first appearance between 635 and 541 million years ago, especially after the first predators had shown up. How have cephalopods’ shells evolved from armors to means of transportation? How have they adapted to further suit these animals’ needs? Watch this video from the PBS Eons series. The ancestors of modern, squishy cephalopods like the octopus and the squid all had shells. Shells helped mollusks move through water, giving them an advantage over similar animals without a shell. Over time, some cephalopods internalized their shell like a backbone, some…