The Mycelium pool is found in the northern area of the Mushroom Forest on Fossil Island. It can be used to calcify fossils into enriched bones. Players can find Irene here, who will explain what the pool is used for.
The pool holds up to 28 fossils, 10 calcite, and 10 pyrophosphite. The fossils can be either unidentified or cleaned. However, plant fossils cannot be enriched and will be instantly destroyed if added to the pool. Unidentified large fossils have a chance to be plant fossils, so cleaning those fossils is not recommended if planning to use them at the mycelium pool.
There is a fossil storage crate next to the pool for easy withdrawal.
Using the pool
Use the hopper to open the Fossil Pool interface and add fossils, calcite, and pyrophosphite. Items can also be selected and used on the hopper, but the current status of the contents will be more ambiguous.
The chemical process begins when there are at least 3 calcite, 3 pyrophosphite and any fossils have been added. The process takes 10 steps to finish and with every step the progress bar gets closer to completing, there is a 1/3 chance for 1 calcite and pyrophosphite to be consumed.[1] The number of calcite and pyrophosphite required does not depend on the quantity or size of fossils in the pool. Adding 8 calcite and pyrophosphite results in roughly 4.3% failure rate, resulting in the use of 8.3 calcite and pyrophosphite on average per inventory of processed fossils. Adding 7 of each results in 14.5% failure rate, resulting in the use of 7.6 calcite and pyrophosphite on average. Any leftover calcite and pyrophosphite is lost.
To avoid prematurely starting the process, add fossils to the hopper and then calcite and pyrophosphite. When the process starts, the message The pool begins to bubble appears in the chat box and the chemical process begins. During this process, bobbing fossils occasionally appear around the pool and they need to be poked back down, otherwise the fossils will dissolve from too much air exposure and be lost one at a time. This occurs every 6 to 13 ticks (3.6 to 7.8 seconds), so standing near the ramp in front of the hopper will maximise the chance to reach one on either side in time. If the number of calcite and pyrophosphite drops to 2 during the enrichment process, progress pauses and more calcite and pyrophosphite must added to the hopper to resume progress. Note: Adding any additional items after the process has begun will lower the progress bar.
The chemical process takes 70.2 seconds (117 ticks) to finish, regardless of the quantity or size of fossils in the pool, and regardless of how much extra calcite and pyrophosphite was added. Once the process progress bar has emptied, a notification will appear in the chatbox, and any unused calcite or pyrophosphite will disappear. Open the sluice gate to move the enriched bones into the rinsing pool to the north, behind the Ancient Shroom, where they can be collected. There must be enough inventory slots to collect all the fossils at one time, otherwise they cannot be collected at all.
Using and confirming opening the sluice gate before turning the fossils into enriched bones will delete all the items in the mycelium pool.
Logging out or switching worlds during the process is safe; the progress bar and contents of the pool will be remembered.
Using the enriched bones
Use the enriched bones on the easternmost strange machine at the House on the Hill, accessed via the magic mushtree south-west of the pool, for Prayerexperience. The experience rates and experience per fossil are shown in the table below. A trip of enriching bones and then using them on the strange machine takes roughly 2 minutes and 30 seconds.
^Jagex. Mod Ash's Twitter account. 17 October 2022. Archived from the original on 17 October 2022. Mod Ash: "Flat chance of 1/3 on each step, if I'm reading this correctly."