The horizontal bands of agte show the orientation of the magma pocket before the minerals began to enter it.  Boytroidalism are what the little domes are at the ceiling of the geode.

weiight = 5.2 oz. width=2.5 inches height = 2,5 inches depth = 1.5 inches

Many minerals display boytroidalism such as malachite and hematite etc. This is an inexpensive sample of true boytroidalism. which is a globular surface. The word boytroidal could be applied to a cluster of grapes as well.

This  incredible little agate has as it's rim "plume agate" or feather agate adding a third phenomenon in its formation.