People going to Laguna Beach, Calif. for the fourth of July were surprised to find dark colored jellyfish swimming in the water.
It is believed that the jellyfish were black nettle jellyfish, a rare type that makes them dark in color with long tendrils.
Swimmers said they felt the long tendrils clinging to their skin and one said a jellyfish was "the size of a hula-hoop."
Some tendrils in black nettles can reach more than 25 feet in length. While the sting can be incredibly painful, it is rarely fatal.
There are photos of the jellyfish dating back to the '20s, but because they are so rare, scientists didn't identify them until 1999.
They are usually never seen in Southern California, but Nigela Hillgarth of Birch Aquarium said that they might be drawn to the area searching for food.
Jellyfish eat mostly plankton, but plankton move towards the shoreline when the ocean temperatures change or due to fertilizer runoff and human activity.
When planktons move towards the shore, jellyfish usually follow them.
Black nettles were first discovered in California in 1989 near San Diego. They then disappeared and returned in 1999.
The sea creatures are usually found in Mexico and Baja California.