evidence: 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. [...] A creepy video captured during a research dive off the coast of Florida shows a deep-sea creature feasting on the head of a fish. The video was featured in the NOAA (National Oceanic and Atmospheric Administration) Office of Ocean Exploration and Research's "31 Dives of Halloween" web series, which is highlighting a host of fascinating deep-sea creatures in the run-up to the popular holiday. [...] Every deep sea expedition returns with footage of new, rare, and/or alien-like creatures. One of the latest such journeys, undertaken by marine researchers aboard the Schmidt Ocean Institute’s 272-foot research vessel Falkor, just brought back vivid footage of life around the protected Phoenix Islands Archipelago, located in the remote Pacific Ocean.