These rare floaters made an unwelcome appearance at several stretches of shore in Laguna Beach over the Fourth of July weekend, sending swimmers screaming to shore.
Although many of the jellies were already dead, smashed up in the surf and rocks, their stingers were plenty capable of stinging post-mortem. Swimmers reported stings all over their bodies, with clumps of the dark membranes clinging to their skin as they fled to the shore.
The black jellies are tough to find, so much so they were only officially identified in 1999. But scientists say they've made an impression: their bells can reach a meter across, not to mention the 25-foot-long tentacles, and their stings are particularly nasty.
They were spotted at Thousand Steps, Table Rock, Diver's Cove and Rockpile beaches in Laguna over the weekend.
Swim Week Miami Beach 2014 [PHOTOS]