Shark Eggs
Each egg case contains one pup, which takes between six and nine months to hatch. Other egg-laying shark species have different egg shapes: this article has pictures of some of them. Most sharks actually give birth to live youngs.
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Monterey Bay Aquarium “Horn Shark” https://www.montereybayaquarium.org/animals/animals-a-to-z/horn-shark last accessed 6. february 2021
Australian Geographic “The weird world of shark eggs” https://www.australiangeographic.com.au/topics/science-environment/2018/08/the-weird-world-of-shark-eggs/ last accessed 6. february 2021
Wourms J.P., Demski L.S. (1993) The reproduction and development of sharks, skates, rays and ratfishes: introduction, history, overview, and future prospects. In: Demski L.S., Wourms J.P. (eds) The reproduction and development of sharks, skates, rays and ratfishes. Developments in environmental biology of fishes, vol 14. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-3450-9_1