World's Oldest Known 'Octopus' Turns Out to Be An Entirely Different Animal

Pohlsepia mazonensis was discovered in 2000 and is known from a single fossil.

The fossil came from the Mazon Creek Lagerstätte in Illinois and was preserved in soft mud about 300 million years ago.

It initially appeared to have eight limbs, two eyes, and an ink sac and was described as the oldest known octopus.

Pohlsepia has been reclassified as a nautiloid, a shelled cephalopod.

The reclassification pushes earliest octopus evidence forward by about 150 million years and pushes nautiloid soft-tissue records back by about 220 million years, making this the oldest soft-tissue nautiloid evidence.