They do give a 1% incremental bonus to gold income ;) (I'm aware that this needs to be better explained in the New Game+ GUI update I'll push later today)
@Dovakin1963 if you are at Hellstone level 1 there are 2236 more to go before you are done...and my blacksmith had a stroke of brilliance an crafted a: Good ULTIMATE PICK +14 P:14.58b Q:1967.8%
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 "Planet Miner - The Search for the Elements of Life"){kind=icon}
 "Frantic Sky"){kind=icon}
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 "Bloons Super Monkey 2"){kind=icon}
They do give a 1% incremental bonus to gold income ;) (I'm aware that this needs to be better explained in the New Game+ GUI update I'll push later today)