Purple

Moon jelly, tossed up by the tide on Oyster Bay beach:

Aurelia labiata. The purple gonads identify this as a male.

The northernmost form, ranging from Puget Sound, Washington, to Prince William Sound, Alaska, have a pyramidal manubrium. .... The bells are peach or whitish, male gonads are dark purple, and female gonads pale brown. (From AnimalDiversity.org)

There were about a dozen of these on the beach, about 6 inches across. All of them had the four purple "horseshoes". They live only one year, but the females brood their young for a short while, so may be slightly longer-lived than the males. (Just a wild guess, trying to explain an all-male collection of a gregarious animal.)

Individuals of this species from cold waters can survive being frozen solid in ice. (From WallaWalla.edu)