I thought ~~have bought~~ this was internet fake. It’s not:

Uraba lugens is nicknamed the mad hatterpillar because of its distinctive exoskeletal feature.[4] Every time it sheds the head portion of its exoskeleton, the exoskeleton stays attached to its body. Over time, developing through its life span, the head grows bigger and sheds increasingly larger exoskeleton shells, which build upon each other.[5]

Wikipedia entry

Well to be fair, that's sounds just something Australian would do

The "an" is off-meter. 😱

We are one but we are many

And from all the lands of Earth we come

We wear old heads, that we have moulted

I am. You are. We are Australian.

So that's what a skull cap is.