Sustenance

Historians who had been allowed access to the "Monster Vaults" of the databanks in the Doctor's TARDIS observed that Abzorbaloffs of Clom were constantly drawing sustenance through their skin and so needed to be as naked as possible, a predilection they shared with the family Slitheen from Clom's twin world of Raxacoricofallapatorius. (PROSE: The Monster Vault)