Ocean researchers believe a rare type of giant jellyfish floated through the waters off of Southern California over the July 4 weekend, stinging local swimmers as it went by.
Some beach-goers near the upscale Laguna Hills community in Orange County returned to the shore with dark membranes clinging to their bodies.
From the color of the membranes, experts determined they may have well come from the elusive black jellies, otherwise known as black sea nettles.
Much about the species' behavior and life cycle, as well as general whereabouts are unknown.
Considered a giant jelly, the black nettles were first named in 1997, though early pictures of the creature were apparently taken in 1926, according to the Monterey Bay Aquarium Animal Guide, which explains the nettle's distinctive purplish bell can reach over three feet in diameter, while its lacy, pinkish arms can reach nearly 20 feet length and stinging tentacles can grow longer than 25 feet.
Scientists suspect the black nettles likely live in deep, calm waters, though large blooms, or floating groups of the jelly, have been spotted in recent years in California coastal waters, most recently in 2012.
Giant black sea nettles appeared along the San Diego shoreline in the summer of 1989, but then suddenly disappeared. Then the giant drifters reappeared again ten years later, in the summer of 1999.
Increased numbers of sea nettles may indicate changing ocean conditions that have filled waters with higher concentrations of nutrients, spurring new growth in plankton, which in turn is consumed by the nettles.
It's also a possibility the appearance of the black nettles in is also related to El Nino/La Nina events.
Nigela Hillgarth of Birch Aquariam in San Diego said warmer ocean temperatures may have brought the jellyfish closer to shore in search of prey where they were caught by the current and drawn ashore.