BOTRYOIDAL

botryoid, botryoidal, boytrose

(adjective) resembling a cluster of grapes in form

Source: WordNet® 3.1

Adjective

botryoidal (comparative more botryoidal, superlative most botryoidal)

(chiefly, mineralogy) Having the form of a bunch of grapes.

Source: Wiktionary

Bot"ry*oid, Bot`ry*oid"al, a. Etym: [Gr. cluster of grapes + -oid.]

Definition: Having the form of a bunch of grapes; like a cluster of grapes, as a mineral presenting an aggregation of small spherical or spheroidal prominences.

Source: Webster’s Unabridged Dictionary 1913 Edition