Quartz:

“A real alien would be a sentient being with no common ancestry with us at all, arising completely independently,” says Godfrey-Smith, who published a book on consciousness and octopuses earlier this year. “We might never meet that—if we do, that would be great. If we don’t, the octopus is our best approximation because there’s a historical connection but it was a long time ago.”

There’s no clear way of evaluating consciousness in other animals (or in other humans, for that matter—it’s quite possible that you’re the only conscious being alive and everyone you know is merely displaying signsof consciousness rather than truly experiencing it). But we can certainly make educated guesses. Broadly speaking, consciousness is often defined as there being an experience of what it’s like to be said creature. (This notion is explored in depth in philosopher Thomas Nagel’s essay, “What is it like to be a bat?”)

Octopuses display signs of curiosity, and Godfrey-Smith believes it’s extremely likely that they’re conscious beings. “I think the exploratory behaviors, the fact that they attend to things, they have good eyes, they evaluate, are little bits of good evidence that there’s something it’s like to be an octopus.”