Octopi don't have external ears, of course. P sure Ina is modelled on this kewt lil' guy, Ophistoteuthis californiana aka flapjack octopus, which is kind of the go-to starting point for "cutesy" cephalopod-based monstergirl designs from what I've seen. The appendages are simply fins, a characteristic trait of the cirrate suborder of octopuses used for propulsion.