@BuffSoul I'd probably put gold bar in it cuz gold value never falls. I would keep restraint on myself and not sell much so as to not break the economic structure...
This could potentially solve the manufacturing industry problems of investing financially in obtaining and refining of iron and steel, and Japan being one of the largest automobile manufacturing country will treat it extremely valuable that means never ending free money again... (but I'd consider the gold option since I would keep it a secret and live life peacefully)
there are never ending options you could choose...you could choose Fossil Fuel or hydrogen in-order to support space research. In that case the rocket wouldn't really run out of fuel and venture and discover the hidden secrets of the universe.
Even though you put a rock in it, a rock is seemingly valuable if financially invested to obtain various minerals and never ending of it could mean never ending money...
PS : I would like to thank you for opening mind and thinking so deeply about something insignificant and illogical.