Fossils have revealed the existence of ancient octopuses that may have reached lengths of up to 61 feet, with some reports suggesting they could have been as long as 100 meters, or the size of a 5-story building. These giant, kraken-like creatures are believed to have lived during the Cretaceous period, potentially as apex predators. The discovery is based on fossilized jaws and other remains that indicate the octopuses were capable of crushing the bones of their prey.