A rare, massive jellyfish stung several beach-goers in Southern California over the holiday weekend, leaving swimmers with dark membranes clinging to their bodies as they came ashore, The Orange County Register reported.
The incident occurred at "Thousand Steps Beach" in south Laguna.
The jellyfish are believed to black jellies, or Black Sea Nettles, based on the color of the sea animal. Their sting is painful but not lethal to humans, but the tentacles may break off if a swimmer bumps into them.
Black jellies are huge. Their purplish bells can reach over five feet, while their stinging tentacles can grow to over 30 feet, according to Monterey Bay Aquarium.
Black Sea Nettles live in deep waters off North America's Pacific Coast. Warming ocean temperatures bring the jellies closer to the shore. The last invasion of Black Sea Nettles happened in August 2012 along San Diego's coast.
Little is known about these giant jellyfish as they were only recognized as a new species in 1997.