White rhinoceros
From Memory Alpha, the free Star Trek reference.
The horn was highly prized among certain cultures of Earth as an aphrodisiac. (ENT: "Fight or Flight") According to USS Enterprise-D primary-school teacher Miss Kyle, "as the value of their horns increased, the number of white rhinos in the wild kept falling, until they finally became extinct" during the mid-22nd century. (TNG: "New Ground")
