Thunder Egg

This is another interesting specimen called thunder egg.
It is a potato-like rough rock on the outside and inside it contains agate mineral.
I love this stylish cool name and also this surprise factor - secret treasure keeping itself hidden from human's hand. Whoever found this in the first place would never have known there was this beautiful agate if he/she hadn't have sliced it half.
This one originally comes from Brazil and travelled across many different oceans and passed through many different owners and finally arrived in my hand.


There is a little green mineral formation, probably a malachite according to John the Rock guy at the market. Looks like an ancient tree frozen in a huge iceberg.


Back of the thunder egg, looks like an ordinary rock or a potato fossil!