crumble
     v 1: fall apart; "the building crimbled after the explosion";
          "Negociations broke down" [syn: {crumple}, {tumble}, {break
          down}, {collapse}]
     2: break or fall apart into fragments; "The cookies crumbled";
        "The Sphinx is crumbling" [syn: {fall apart}]
     3: fall into decay or ruin; "The unoccupied house started to
        decay" [syn: {decay}, {delapidate}]
Source: WordNet® 2.0