What're ten centimeters across, live 6 miles under water, and are incredibly toxic? The Xenophyophores of the Mariana Trench—the largest single-celled organisms in existence.
Their existence was confirmed during a recent survey conducted by the Scripps Institution of Oceanography at UC San Diego and the National Geographic Society along the Sirena Deep section of the trench. They had previously only been found as deep as 4 miles, though they are prevalent on many of the ocean's abyssal plains.
Xenophyophores are marine protozoans. They feed by sifting through sediments on the sea floor, excreting a slimy substance as they move along. With populations reaching densities of 2,000 individuals in a 100 square meter area, the slime carpet can resemble Zerg Creep. And since these animals continually root through sediment, they tend to absorb massive quantities of lead, uranium and mercury—so no, they aren't edible. [NOAA - Wikipedia via Live Science]