Horn
From Tardis Wiki, the free Doctor Who reference
On Earth in 100,000 BC, Ian Chesterton found an animal skull with no horns or antlers, suggesting that it came from a horse. (TV: An Unearthly Child)
The Judoon had horns. Removing the horn of a Judoon captain was considered a dishonour and therefore the worst of insults. (TV: Fugitive of the Judoon)