Ecotopian durable plastics, which are used for minibus bodies, “extruded houses,” coins, bottles, and mechanical objects of many kinds, have molecular structures similar to those of our plastics, and are virtually decay-proof under ordinary circumstances—in particular, so long as they are not in contact with the soil. However, by chemical advances that have so far remained secret, Ecotopian scientists have built into these molecules “keyholes,” which can be opened only by soil micro-organisms! Once they are unlocked, the whole structure decomposes rapidly.
