Though Pompeii worms were initially discovered in the 1980s by French researchers, it was not until 21 years later that it was identified as the most heat-tolerant animal on earth. The Pompeii worm otherwise referred to as the "bristle worm" is an extremophile that can be found near "chimneys" deep in the Pacific Ocean from where superheated water is discharged from within the Earth’s crust.
Contrary to belief, the bottom of the deep ocean is not completely barren of life mainly due to hydrothermal vents as this excerpt explains: "Hot, mineral-rich fluids supply nutrient chemicals. Microbes, some of which eat these chemicals, form the base of the food chain for a diverse community of organisms. These vents are the only places on Earth where the ultimate source of energy for life is not sunlight but the inorganic Earth itself."
Named after the ancient Roman city of Pompeii, the Pompeii worm is described as a deep-sea polychaete that resides in tubes near hydrothermal vents along the seafloor. They are known to reach up to 5 inches in length and are pale gray with red tentacle-like gills on their heads.
An amazing fact about these worms is that while their tail ends can rest in temperatures as high as 176º F, their heads stick out of tubes into waters that are much cooler at 72 °F.
The secret to being able to thrive in such extreme temperatures is attributed to a bacterial coating as this excerpt explains: "The woolly worm scuttles back and forth between the hot water rich in nutrients and the cool water rich in oxygen—movement that also mixes cool water into the tube. But more importantly, a fleece-like layer of bacteria helps insulate the Pompeii worm from the extreme heat."
Through a symbiotic relationship, the Pompeii worm provides sustenance to the bacteria by secreting mucus, and the bacteria in turn redistributes the heat to keep the worm cool.