Which whale's skin is usually wrinkly?

Click on Wikipedia link under answer for whole article. The whale is named for the waxy/oily substance in its head. It was used for lamp oil and candles. Sailors originally mistook the oil for sperm and called it spermaceti. Ceti means whale.

I wonder how it got its name?

Player #7719043, Shrinkage, at least that's what George Costanza claims.

while the sperm is the smallest cell in a male human's body, why on earth did they call the world's largest animal a "sperm" whale?