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 that its bite had the force to crush bone, and commented that it was interesting. (TV: Genesis of the Daleks)