That's one of the reasons why repotting is needed. Used to inoculate the soil with even more soil fungi. Same as above. A handful in a batch. Volcanic rock used for landscaping mulch.
Many roots grow into the porous rock and out the other side.
Ace Hardware sells a Rayon mop head. The strings pulled from the mop are allowed to hang out the drain holes in the pot. In any potted plant, there is a puddle of water called a perched water table. It's a little like a bead of water on a newly waxed car only it's in the bottom of the pot. Roots need air.