Unicorns are a class of mythological beast found in European folklore and mythology. Usually depicted as a white horse with a single horn spiraling from its forehead, the unicorn is associated with purity and grace. In folklore of the middle ages a unicorn could only be captured by a virgin maiden. According to some sources this tale was an elaborate allegory for the incarnation of Christ unto the Virgin Mary. The horn of a unicorn was thought to have magical healing properties. Many of the "unicorn" horns found in European collections were actually the long spiraling tooth of the narwhal whale. Interestingly some of the earliest objects unearthed from Harappa and Mohenjo-Daro (early South Asian Indian civilizations) were small stone seals inscribed with animals, including a unicorn-like figure in one. These seals are dated back to 2500 B.C.