A video posted by David Scheel of Alaska Pacific University as a part of PBS’s Nature show captures an octopus named Heidi sleeping, and possibly dreaming. In his voiceover, Scheel explains why he thinks the cephalopod may be dreaming.

While evidence of REM sleep has not so far been seen in octopuses, they do have a kind of “sleep twitch” of their own. Sleeping octopuses “flicker”. As they rest, neuronal firing in their optic lobe causes their pigment-containing cells (chromatophores) to become active. And so, they shift colours and patterns while resting, as if responding to something only they can sense.

Sy Montgomery writes on the fascinating, deep intellect of octopuses for Orion Magazine, as they have long been studied for their keen intelligence and sensitivity.