The term 'Eggy MASS' is a combination of two words, 'Eggy' and 'MASS'. The first word, 'Eggy', is a reference to the egg-like shape of the MASS, while the second word, 'MASS', refers to the large amount of material that makes up the eggy MASS. The crossword solution for this term is 'ROE', which is a type of fish eggs. ROE is a collective term for the fully ripe egg masses of certain fish and shellfish, such as salmon, carp, and shad. It is used in many cuisines around the world and is considered a delicacy in some cultures.