breakable brown brown-eggs calcification calcium-carbonate chicken-eggs colored coloring colors coloured colouring colours cook cooking egg eggs eggshells external farm-fresh food fragile fragility fresh fresh-eggs haemoglobin hemoglobin hens-eggs life mottled mottling outer-covering outside oval oviduct ovoid pigmentation pigmented-shells pigmenting protoporphyrin speckled surface surfaces surfacing texture textured textures variety various