These are a rare formation that has what look like little towers growing all over the sides. These are also known as “light library” or “lightbrary” crystals.
They are teaching crystals that contain separate chambers, they work well for groups as each person may access different chambers at once. You can access wisdom from the crystalline teaching realms also known as the “light libraries”.
They are a gateway to access akashic records of crystal teachings as well as your own past life knowledge of the crystalline realms.