Mariana Trench
On their 1960 descent, the crew of the Trieste noted that the floor consisted of diatomaceous ooze and reported observing "some type of flatfish, resembling a sole, about 1 foot long and 6 inches across" lying on the seabed. The report has since been questioned, with suggestions that it may have been a sea cucumber. The video camera on board the Kaiko probe spotted a sea cucumber, a scale worm and a shrimp at the bottom. At the bottom of the Challenger deep, the Nereus probe spotted one polychaete worm about an inch long.