They were unaffected by gunfire and explosions and could use their claws as weapons to create explosions of their own. Under Omega's command they attacked UNIT HQ. They killed a number of soldiers, captured the Third Doctor and his friends, and took them to Omega. (TV: The Three Doctors) The Gell guards were one of the species referenced in Theoretical Monsters: A Credibility Test. (PROSE: Interference - Book One)