We've discussed whether crumbs or smaller fragments are still the Body of Christ.
“The Eucharistic presence of Christ begins at the moment of the consecration and endures as long as the Eucharistic species subsist. Christ is present whole and entire in each of the species and whole and entire in each of their parts, in such a way that the breaking of the bread does not divide Christ.” (CCC 1377; cf. Council of Trent, Session XIII, Canon III)
Here is a very good article on the subject:"Fragments" of the Eucharistic Species