it's interesting how the constraint of being in water limits inhabitants from developing technologies like fire and throwing projectiles for hunting. octopuses seem like they have the physiology and neurology to figure out projectiles and even grinding a sharp point, but that strategy wouldn't give them the same boost it did early humans because of the drag of water. construction and engineering is also made difficult by tides and erosion so they don't take it much farther than piling up some shells and rocks for a little sleep spot.