i decided to try mining straight down with TNT and see what would happen, after seeing the indestructable rock i decided to walk down to see what i could find, after finding 3 blocks of diamond ore, a little gold and LOTS of metal ore, i saw what appeared to be a water pool next to a lava water fall, what i did realize until i got really close was that it was the "bottom" of the map :D

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Planet Core.png