Squalene

Squalene is a low density compound often stored in the bodies of cartilaginous fishes such as sharks, who lacking a swim bladder must reduce their body density with fats and oils. Squalene, which is stored mainly in the liver (thus the common name "shark liver oil"), has a specific gravity of ~0.86.

Recently it has become a trend for sharks to be hunted to process their liver for the purpose of making squalene health capsules. However there is little clinical evidence to prove that these capsules do anything to increase individual's quality of life.

Squalene is also found in small amounts in the human body, when cholesterol is converted into fat.