I’ve always had a certain fascination with octopuses*. They are a spectacular example of a life-form that is, in most anatomical respects, radically different from the tetrapod paradigm that’s dominant among land animals – the four-limbed, internal skeleton pattern, centred around a spinal cord, found with various modifications among amphibians, reptiles, birds and mammals. 
Moreover, they’re a life-form that displays very marked intelligence, dexterity, and a whole collection of cool abilities.
I recently learnt, however, that their intelligence at the moment is held back very considerably by two facts. Firstly, their lifespan is short, and reliably so, because after reproducing they release suicide chemicals (not to mention having given up food while establishing their young). And secondly, although they are often quite social and interact with each other, there is no parental care, with the babies just floating off into the current.