How many letters does the top answer for “a peculiar organic red coloring matter found in the feathers of various birds.” have?

The most common answer is zooeerythrine (13 letters).

Crossword clue: a peculiar organic red coloring matter found in the feathers of various birds.

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

zooeerythrine 13 letters web-def

A peculiar organic red coloring matter found in the feathers of various birds.

zooerythrine 12 letters web-def

A peculiar organic red coloring matter found in the feathers of various birds.