Simple past tense and past participle of crumble.(verb)
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Use "crumbled" in a sentence
"These are rounder in shape, about 25% crumbled from the pellet form into loose salt, and very dirty (black specs/rocks in the pellets and loose in the crumbled salt.)"
"In many ways, Regina is the perfect performer for the occassion: Russian-born, she was part of the large emigration of Russian Jews to Israel and the United States when the Iron Curtain crumbled in the late 80s."
"It is supporters like these for a candidate like Clinton, which is why her campaign crumbled from the start."