Giant clam
From Tardis Wiki, the free Doctor Who reference
The Giant Clam was one of the unwanted 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 were seen. The Fourth Doctor said its bite had the force to crush bone and commented that it was interesting. (TV: Genesis of the Daleks)