“When I was a student, one jumped out of a tank and traveled down the hallway,” said Jenny Hofmeister, who’s now a postdoctoral scholar at the Scripps Institution of Oceanography in San Diego. In 2016, an octopus named Inky became a legend when it slipped out of its tank, slithered down a pipe, and escaped into the ocean.

Hofmeister speculates that overcrowding from booming populations could have prompted the octopuses out of the water en masse. One study published in Current Biology in 2016 found that, as fishermen take more and more of the large animals that feed on octopuses, their populations have boomed. This means the invertebrates would have to travel farther to find food, and perhaps equally important to an octopus, shelter. And that drive could have pushed them toward land, Hofmeister speculated.