A calving iceberg exposed a region that never before had been seen by human eyes, revealing a vibrant, thriving ecosystem

While operating the deep-sea robot nearly 7,000 feet below the surface, the machine’s camera captured a creature that appeared to be “all legs” walking across the seafloor, according to a March 18 Facebook post from the institute. “Huge spider alert! This is a pycnogonid,” researchers said in the post.

Giant sea spiders, octopuses, ice fish, corals, and sponges—some likely to be hundreds of years old—were discovered in a newly exposed stretch of the ocean after a colossal iceberg, roughly 19 miles long,