Space-shark

A space-shark was a type of ship used by the Pyrons. They carried both plinium and zargon missiles, and were around 60 feet in length.

When the Fifth Doctor and Adric landed on Vaga, they were detected by the Pyrons who sent a space-shark to destroy them. Despite its bombardment, it was unable to kill either of them. A Vagan inter-dimensional craft appeared and used a beta-force field to prematurely detonate the space-shark's warheads, destroying it completely. (PROSE: The Key of Vaga)