Mercurian Cave-cats are a non-sapient predatory species from Mercury.
They have a 20 ft body length (6.096 m) with eight legs, four eyes, and a tail armed with bone barbs. They are highly resistant to bullet injury and therefore can remain alive for a long time after being shot. However, a shot straight through the brain will kill them immediately. Since their brains are proportionally small compared to the head as a whole, this can be a difficult task even for experienced hunters.
- "The Halfling", by Leigh Brackett (1943)