What are the best answers for “a spheroidal fullerene; the first known example of a fullerene”?

buckminsterfullerene, buckyball.

How many letters does the top answer for “a spheroidal fullerene; the first known example of a fullerene” have?

The most common answer is buckminsterfullerene (20 letters).

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

buckminsterfullerene 20 letters wn-def

a spheroidal fullerene; the first known example of a fullerene

buckyball 9 letters wn-def

a spheroidal fullerene; the first known example of a fullerene