Giant clam
From Tardis Wiki, the free Doctor Who reference
The Giant Clam was one of the unwanted bi-creations of Davros' experiments. They were kept under the Kaled Dome, in a cave leading out to the Wastelands. There was more than one Giant Clam, five in total were seen. The Doctor also said it had the biteforce to crush bone and commented that it was interesting. It is unknown what other animal mutations Davros had created. (DW: Genesis of the Daleks)
