In the essay noted here, philosopher Godfrey-Smith takes on the question of what invertebrate intelligence feels like. Invertebrates have a distributed body plan so it would have to feel like your arm is part of yourself but also part independent. The reason this is of interest is that I noted here, octopuses and squid are unusually intelligent:
Some invertebrates, especially mollusks, are also unexpectedly intelligent. Underwater footage shows that, in the first known example of tool use among octopi, one species of octopus has learned to dig up and use discarded halved coconut shells as a shelter.
Neatly halved coconuts are a human discard, so the behavior may actually have been learned in recent millennia. Researchers think that the octopi were using some less satisfactory material before, but they had the intelligence to just switch. More.