Pyrodictium are found in the porous walls of deep-sea vents where the temperatures inside get as high as 400 °C, while the outside marine environment is typically 3 °C.
The thermal stability of Pyrodictum occultum's isolate tRNA has been analyzed, indicating that modifications in the nucleosides allow the organism to withstand temperatures well over 100 °C.
While the exact reason for this morphology is unknown, it is likely that the range of motion provided by the cannulae allow the cells to move freely when by the thermal energy from the extreme heat of the organisms's environment.
The large size range of the cells may allow Pyrodictium to inhabit a variety of pores in the deep-sea vent walls.
Their ecological significance remains a mystery because of the difficulty in collecting samples which may yield data on the abundance and diversity of these extremophile.