Verbs

(v)crumble, crumple, tumble, break down, collapsefall apart“the building crumbled after the explosion”, “Negotiations broke down”
(v)crumble, fall apartbreak or fall apart into fragments“The cookies crumbled”, “The Sphinx is crumbling”
(v)decay, crumble, dilapidatefall into decay or ruin“The unoccupied house started to decay”