I remember that in pikmin 3 rock and winged pikmin actually had unique soul shapes when they died; They don't have that shape anymore in pikmin 4 but I feel like Nintendo should've brought that back not just for them but also maybe make unique soul shapes for the other types (it doesnt have to completely change, just tiny changes to differentiate and diversify the souls in another way other than the colours) it would've made it look more interesting
