Terrapratch

Terrapratches were giant turtles which moved in space. They could live in the breathable atmosphere that surrounded their shells. The Eleventh Doctor, Amy Pond and Rory Williams encountered a race of unwitting parasites which had unknowingly been living on a fatty, white substance beneath one Terrapratch's shell. The Terrapratch grew weaker and endured great pain, causing disruptive and frightening earthquakes believed to be the work of Sky Goblins. The Doctor encouraged a happier co-existence by using photographs taken from the TARDIS whilst hovering above their worlds. (COMIC: The Parasites)

Behind the scenes
The turtles show similarity to those from. Terry Pratchett wrote those stories, with a portmanteau of the author's name sitting in for the species' own.