Sperm whales are easily recognized by their massive heads and prominent rounded foreheads. They have the largest brain of any creature known to have lived on Earth. Their heads also hold large quantities of a substance called spermaceti. The substance was named in the mistaken belief that it was the coagulated semen of the whale. Scientists have yet to understand its function, but believe it may help the animal regulate its buoyancy or aid in echolocation. From the early eighteenth century through the late 20th the species was a prime target of whalers. Spermaceti was used chiefly in ointments, cosmetic creams, fine wax candles, pomades, and textile finishing; later it was used for industrial lubricants. There is even controversy on the Internet on whether or not NASA used Sperm oil to lubricate the Hubble telescope, since it remains liquid at sub-zero temperatures. Whales in Space