Giant clam
Giant clams were one of the products of Davros' early experiments. They were kept under the Kaled Dome in a cave leading out to the Wastelands. The Fourth Doctor said that its bite had the force to crush bone. A giant clam bit Harry Sullivan's leg as he and the Doctor were exploring the caves. The Doctor subdued it by hitting it with a rock. Although they're evidently mobile, the Doctor noted that they were not very fast, and Harry in turn speculated this was the reason Davros abandoned them. (TV: Genesis of the Daleks)
Kwol recalled an occasion when Chris Cwej got his foot stuck in a giant clam during an excursion to "one of the Sub-Enemy worlds". (PROSE: When I Remember __________)