The mycelium pool can calcify fossils into enriched bones via a chemical process. This uses both pyrophosphite and calcite crystals. To do so, players must add the fossils, calcite, and pyrophosphite to the hopper. Players should add enough crystals to the hopper so that the chemical process can occur. When players have added enough, the message The pool begins to bubble will display in the chat box. Calcite and pyrophosphite must be added first or most fossils will be destroyed.
Whilst the chemical reaction is happening in the pool, the calcite and pyrophosphite will begin to be consumed, thus players must add more in order to maintain the chemical reaction. In addition, players must pop bobbing fossils that surface around the pool, otherwise the fossils will become too exposed to air and dissolve.
Once the process progress bar has reached zero, players must open the sluice gate behind the Ancient Shroom, and check the rinsing pool to obtain the enriched bones the player deposited in the hopper. These bones are then used on the easternmost strange machine in the House on the Hill to receive Prayer experience.
- The placement and appearance of the Ancient Shroom in the middle of the pool is a likely reference to the mushroom people of the Dark Souls series.