I second this recommendation. I think someone in HN recommended this, very fascinating. My respect and interest for octopuses and surprisingly cuttlefish went way high up after reading this book. Kudos to whoever recommended it!

It feels like we are wasting our time looking for aliens searching for them in the skies (especially the unscientific work around oumuamua).

They are living right beside us in the form of cephalopods. We haven't deployed enough science on these amazing creatures yet (without of course distributing them like putting them in cages), probably because it's not a sexy field as compared to say astronomy or other cool things...