crusta
(ˈkrʌstə) n,
pl crustae1. (Anatomy) a hard outer layer, esp in anatomy or pathology
2. (Pathology) a hard outer layer, esp in anatomy or pathology
3. (Antiques) an embossed plate inlaid on an object
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014