One of the things I love most about the deep ocean (which you can explore in greater depth with the wonderful Sir David Attenborough-narrated "The Deep," from The Blue Planet) is the way it constantly defies our expectations. Seems like every time someone goes down there, they find something we've never seen before; often, something we've never even considered.
When we dove down in the submarine, we noticed the water became murkier as we got closer to the bottom. There was this turbid layer, and you couldn’t see a thing beyond it. We just saw this cloud but had no idea what was causing it. As we slowly moved down to the bottom of the seafloor, all of the sudden we saw these things,” he continued. “At first, we thought they were biogenic rocks or structures. Once we saw them moving—swarming like insects—we couldn’t believe it."
More details can be found in the WHOI's press release, as well as in this longer video.
In April 2015, a research team studying biodiversity at the Hannibal Bank Seamount off the coast of Panama captured something unexpected—unique video of thousands of red crabs swarming in low-oxygen waters just above the seafloor.