Sea urchins spotted wearing ‘hats’ at strange party on Atlantic seafloor, video shows

Researchers stumbled, uninvited, onto a strange party on the seafloor, video shows — but even more unusual, there appeared to be a strict dress code to attend.

Light from a remotely operated vehicle reveals a “huge” crowd of sea urchins, gathered in the dark roughly 1,350 feet below the surface, all wearing “hats,” made of debris, on the tops of their dome-like bodies, video captured near the U.S. Virgin Islands shows.

The gathering of at least 35 conolampas sea urchins “was a singular and rarely seen event,” the National Oceanic and Atmospheric Administration, which shot the video, said.

Unlike other species of sea urchin, conolampas prefer deeper waters. They had likely come together in order to reproduce, forming a “mating aggregation,” according to the NOAA.

“These animals live by digging and plowing through sand and sediment, leaving very distinctive, meandering trails behind them,” researchers said. Video shows the gathering area covered in long shallow divots, like shoe prints dotting a dance floor.

But the video raises a lot of other questions about the sea critters and what they were up to. Namely, their attire.

“What is the deal with those little debris ‘hats’ and why are all the urchins wearing them???” researchers were left to wonder.

Urchins have been documented picking up debris before, a behavior dubbed “collecting.” But the scale and circumstances make this a highly unusual phenomenon, the NOAA said.

Every single urchin placed their debris at the exact same spot on their bodies, as if wearing some kind of uniform.

Researchers don’t know if the hats are part of some sort of mating ritual, or if sea urchins just like to look dashing.

Some experts have suggested that the species of urchin may sometimes put debris on top of its body in order to “protect their genital pores,” according to the Smithsonian, but this is unproven.

Whatever the case, scientists believe the behavior at the gathering “was too consistent to be incidental,” the NOAA said.

This story was originally published January 3, 2023 at 1:03 PM with the headline "Sea urchins spotted wearing ‘hats’ at strange party on Atlantic seafloor, video shows."