We show a remarkable property of the CM-wild variety P-1 x P-2 , namely that the only ACM sheaves moving in positive-dimensional families are Ulrich bundles. A complete classification of the non-Ulrich range is given.
We prove that this feature is unique in the sense that any other ACM reduced closed subscheme X subset of P-N of dimension n >= 1 belongs to the well-known list of CM-finite or CM-tame varieties, or else it remains CM-wild upon removing Ulrich sheaves.
