Spermaceti organ

Elongated sack of connective tissue containing the spermaceti on top of the head of the sperm whales

Its function is a matter of debate, but it may be used to control the whale's buoyancy in the water and possibly as an acoustic lens to direct sound beams for echolocation

The organ contains a mass of weblike pipes filled with a yellowy wax. It can be cooled or heated, possibly by water being sucked in through the blowhole, and thus shrinks and increases in density (helping it to sink) or expands and decreases in density (lifting it back up to the surface).