How do we know if an organism is sentient?
One of the easiest things to look for is if it is capable of tool use. The Teuthos do not wear 'clothes', so the first and easiest metric is no use to us. What about other forms of tools? Here, it is a little harder to judge. We see no factories, no workshops or agricultural landscaping as we are used to on Earth - but look closer and it is irrefutable that the world, the planet itself, appears to have been shaped by a deliberate, sentient consciousness.