When I look at the World Map, I see an Icon like a face / skull ... sorta pear shaped. Resembles a face.

It appears at different spots on the map. If I fast travel there, usually there is nothing but open space.

Its where your current "used" power armor is when you are not in it

Yeah, shows the location of your most recently worn power armour, really useful if you had to leave it to behind while you went to find more fusion cores, or to know which settlement you left it at.

Strange ... my PA got " stolen " the other day. I left it inside the doors of the Freedom Museum and when I went back the next day it was GONE!!!

Found it standing in the middle of a street in another town. Wish I had known that's what that symbol was.

Thanks for the info.

Just take the core out of the armor if you don`t use it, so it can`t be stolen.

Yeah, I always take the keys to my car when I park it. Or, rather, them, now that I've got my baseball team of PA suits going!