Having been given ribs or ridges, or bearing a costate (ribbed) structure; a variant or emphatic form of costate.
From costate plus -ed suffix, sometimes used to emphasize the ribbed quality or to describe something that has developed ribs, though costate is more standard.
Costated is a bit redundant—scientists prefer just 'costate'—but it shows how -ed can turn an adjective into what feels like a past participle, making it sound like something 'became ribbed' rather than 'is ribbed.'
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