Paleodictyon nodosum is a Mysterious creature thought to produce a certain form of Paleodictyon burrow found around mid-ocean ridge systems in the Pacific and Atlantic Oceans. Although scientists have collected many of the burrows of Paleodictyon nodosum, they have never seen a live one. What a live specimen would look like is widely debated, with the debate being split into two main sides. Adolf Seilacher who discovered the original fossils of Paleodictyon nodosum hypothesizes that the creature is a worm-like species that burrows into the sediment around hydrothermal vents and deflects water flow through the burrows to catch food or farm its own food. Peter A. Rona, discoverer of the modern burrows, suggests that Paleodictyon nodosum may actually be a large protist. There are other known examples of protists reaching the sizes that Paleodictyon reaches, and they are known to be infaunal. Scientists ran various tests on the burrows of Paleodictyon and were unable to reach a single conclusion as to the form of Paleodictyon. The one thing that they can agree upon is that there are many markers that suggest that these forms are caused by a creature, and not by geological forces.