Book 32, Question 76
Why are many reptile eggs leathery instead of hard?
Many snake and lizard eggs, and some turtle eggs, have shells that feel like soft, bendy leather.
The soft shell lets the egg take in moisture from damp soil and swell as the baby grows. It also lets tiny amounts of air pass through. A hard shell would not stretch, but a leathery one can. Soft shells work well when eggs are buried underground.