Re: Na'vi anatomy
Not very, since it is a homologous organ adapted from one present on pretty much every animal it is related to, going back about half a billion years in the evolutionary tree.
"There is no reason why good cannot triumph as often as evil. The triumph of anything is a matter of organization. If there are such things as angels, I hope that they are organized along the lines of the Maffia." - Winston Niles Rumfoord.