Watching carefully, I noticed that two other activities added to the commotion: sloughing of skin and defecation. Like other whales, sperm whales shed skin on a regular basis. This may be a mechanism to reduce the risk of infection and to rid the animals of external parasites. As the whales rubbed against one another, the physical contact dislodged flakes, sometimes entire sheets, of skin, which floated in the water like a blizzard of translucent dandruff.
Group defecation also seemed to play a prominent role. When a dozen or more whales defecated simultaneously, it created a cloud of poop that engulfed the ensemble, obscuring them from view and turning the seawater into an oily soup.
I think it's a metaphor.