manna lichen

noun

1

: any of several Old World lichens of the genus Lecanora (especially L. esculenta, L. affinis, and L. fruticulosa) that have semicrustaceous scaly-foliose or fruticose thalli that roll up and are blown about often in large quantities over the African and Arabian deserts and are much used there for food by people and animals

2

: a lichen (Gyrophora esculenta) used in Japan for food

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