The common “mermaid’s purses” found on our beaches are from the cat sharks (some are commonly called dogfish).
The egg cases of sand sharks are larger and instead of tendrils (like the ones above which attach to seaweed etc) they have ‘horns’ from their four corners.
These sharks are oviparous, which is to say their young develop in egg cases which get their nourishment from a yolk sac. 40% of sharks lay eggs.
About 60% of the shark species give birth to live young. Some grow from a yolk and are then born alive, others live off their siblings and the third group have a placenta to nourish the pup.
More info can be found in the Information Booklet in each cottage.