Slemos

Slemos was a planet visited by the First Doctor. A monster from this planet stowed away on the TARDIS after attaching itself to the Doctor's coat. (PROSE: Stowaway)

Features
Slemos was a steamy swamp planet, with "murky undergrowth". It was defended by Guardians, including the Guardian of Good, who was telepathically connected to the monster called "The Green Terror". (PROSE: Stowaway)