Fossil

Fossil is a buildable raw mineral used primarily as an industrial input rather than a common construction material. It appears naturally in Oasisse, where it is found in the Oil Biome and, in smaller quantities, the Tide Pool Biome. In addition, the Ancient Specimen story trait can produce Fossil from Diamond at a 1:100 ratio after the trait is completed, and the Fossil Fragments generated near its points of interest can be excavated for large deposits of Fossil.

Its main use is in the Rock Crusher, where it is converted into Lime for Steel production as an alternative to Egg Shells. Unlike most other materials processed in the Rock Crusher, Fossil does not turn into Sand. Instead, it breaks into Lime and Sedimentary Rock.

• 100 kg Fossil produces 5 kg Lime and 95 kg Sedimentary Rock.
• Fossil can be used for general building, but this is usually secondary to its industrial value.
• Because it yields Sedimentary Rock instead of Sand, Fossil is one of the few Rock Crusher inputs that does not add to the map’s sand problem.
• In Oasisse, Fossil is a useful early source of Lime if Egg Shells are limited or unavailable.

Oasisse has unusual resource pressure, and Fossil fits into that economy well. The asteroid starts with less natural Water than other starts, much of the map is occupied by hot sand, and the usual Frozen Biome is absent by default. Since Steel production is important for advanced infrastructure, Fossil deposits from the Oil Biome or the Ancient Specimen trait can be an important support resource. This is especially relevant on Oasisse, where the map also lacks natural Wolframite, making some industrial paths more constrained than usual.

When planning around Fossil, it is worth remembering that it is not a renewable industrial resource by itself. The natural deposits come from map generation, while the Ancient Specimen output depends on the story trait. If a colony intends to rely on Fossil for steady Lime production, the player should preserve deposits for the Rock Crusher rather than spending them as building material.