Botryoidal

A botryoidal (/ˌbɒtriˈɔɪdəl/ BOT-ree-OY-dəl) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek βότρυς (bótrus), meaning "a bunch of grapes".

Similar habits are reniform (kidney-shaped) and mammillary (breast-shaped or partial spheres).

Minerals take on a botryoidal habit when they form in an environment containing many nuclei, specks of sand, dust, or other particulate matter to serve as sources of crystal nucleation.

As these spheres grow, they can run into or overlap with others that are nearby, fusing together to form a botryoidal cluster.

This is how the habit can be observed in a variety of minerals that otherwise display distinct euhedral forms.