Nemesis CEO Frostwood accidently caused a universe wide shortage by creating a lucrative constructor start package. Constructors are now found digging everywhere for the now precious rock. Even places that have no limestone.

Limestone¹

I started on Phobos as a constructor, in a place with no Iron on the market and no local limestone, but I’m sure I’ll make it work

says new constructor Dobri, digging frantically on Phobos, a planet without limestone.

Reaching CEO Frostwood for comment,

Unlike the last time Nemesis tried to manipulate the Limestone market, this time it was a unfortunate accident. Any massive profit off these truly regrettable set of circumstances is accidental

Whether or not the Limestone shortage is a elaborate Nemesis ploy or a accident remains to be seen.