Nudibranchs attach their eggs to a solid foundation such like rocks and parts of the reef. Most sea slugs lay each egg in separate capsules which are attached to each other in a long string. To feed the developing embryo, a portion of yolk is normally deposited the egg in each capsule.
Most egg masses are white but for species they are brightly coloured like yellow or red. The classic egg masses of Spanish Dancers are bright red and noticeable to predators, at the same time the red egg masses other species seems to be camouflage by matching the colour of the sponge they are attached. With some species the colour change as the eggs develops from freshly laid to just before hatching. For most species this takes 10-15 days. It looks like an easy pray for fish or crustaceans but the egg masses are left alone. This is thought to be because they simply are distasteful, probably due to the diet of the adults. There is some data suggesting that eggs are protected by antifeedant molecules injected into the band. Exactly what makes them distasteful remains unknown.