Cat sharks' egg cases have tiny, tiny tendrils will that wrap tightly onto plants in the ocean. A horn shark's eggcase settles in big cracks in the ocean's rocks. Many other egg cases settle on the soft seabed. Each little egg is in a hardened sack. It hardens to protect the small pup.
Egg cases are very long lasting.
The eggs take nine months to hatch, just like a human baby. The pups look exactly like their parents, only tinier. The pup is hatched when it is nearly full grown. It wanders off to some place safe. Many pups are eaten as soon as they are born by other sharks.