Locals strolling Huntington Beach recently in Southern California came across a weird sight: thousands of gelatinous pink sea creatures had appeared on the sand. People described the creatures as squishy, almost like jellyfish, and bewildered National Oceanic and Atmospheric Administration scientists, according to NBC Los Angeles.

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The appearance of the unusual creatures sparked social media speculation. Ryan Rustan, a local, posted that the creatures were like little water balloons that popped underfoot. Beachgoer Don Coursey posted on the Huntington Beach Community Forum on Facebook that the creatures burrowed in the sand.

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Huntington Beach Marine Safety Lieutenant Claude Panis said the creatures might have washed up due to El Niño, and that there were also more stingrays closer to the shore than normal at this point in the year. He told The Orange County Register, “There’s all kinds of weird things happening. It’s just strange.” Huntington Beach Marine Safety Lieutenant Eric Dieterman said people had seen the creatures in the past, but there hadn’t been so many before.

So, what are they? California State University, Long Beach professor Christopher G. Lowe told KTLA the university’s expert on invertebrates said the creatures are sea cucumbers. University of California, Irvine associate professor Matt Bracken said the creatures are pelagic tunicates, also known as sea salps. He told The Orange County Register, “These marine invertebrates look sort of like jellyfish, but they are actually more closely related to vertebrates (e.g., humans) than to other invertebrates. They occasionally bloom off the California coast.”

Via the Los Angeles Times and The Orange County Register

Images via Don Coursey on Facebook and Ryan Rustan on Facebook