This is a type of accidental root that grows from a tree's wide horizontal branches, hangs down, and eventually enters the earth.
They appear to be pillars as a result of this. Prop roots are found in plants such as Ficus benghalensis (Banyan tree), Rubber plant, Corn, and others.
When these roots are young, they can absorb water, and as they mature, they provide support to the plant.
Ficus aerial roots begin as epiphytes but eventually penetrate and establish themselves in the soil.