Six Legs

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You may be looking for Six-legged camel.

The Six Legs were creatures native to Syra. They looked like six-legged camels.

They were used as transportation by the Syrans, with the Eighth Doctor and Liv Chenka receiving one, whom the former nicknamed "Muffin", from Mariam to travel to the volcano. River Song and Helen Sinclair later used another to get there. (AUDIO: The Sonomancer)