botryoidal

This term is a specialized geological descriptor used almost exclusively in mineralogy and petrology. It describes a specific growth habit where minerals form rounded, radiating aggregates that mimic the appearance of a bunch of grapes. Because of its technical nature, it is rarely encountered in general conversation and is typically reserved for scientific reports, museum labels, or academic textbooks.

While the word describes a visual shape, it implies a specific crystalline structure—typically radiating acicular or fibrous crystals—rather than a random collection of spheres. It is distinct from "reniform," which describes a kidney-shaped mass, though both describe rounded mineral surfaces.