Origin of egg case
Examples from the Web for egg case
The size of this egg-case depends on the size of the species, ranging from three to about eight inches in length.
This egg-case is not wholly filled with eggs but has a considerable air-chamber in it, causing it to float.
They remain for a short time after hatching in the egg-case, feeding on each other!
How the cockroach deposits its egg-case; a study in insect behavior.The Biotic Associations of Cockroaches|Louis M. Roth
One egg-case of a ray may sometimes contain several eggs and develop several young.