The cocoa bean testa (shell) makes

The cocoa bean testa (shell) makes up about 12% of the weight in fermented and dried cocoa beans. A maximum of only 1.0–1.5% of testa residues is generally allowed in the nibs (beans), so shelling is followed by winnowing. Most contaminant fungi are present in the testa, especially Aspergillus, Eurotium and Absidia species
and are almost completely removed bywinnowing