Here's why:
* Ear development: Ears develop differently in mammals than in animals that lay eggs (oviparous animals).
* Mammalian ears: Mammals have external ears (pinnae) that are used to collect sound waves. Mammals give birth to live young.
* Oviparous animals: Animals that lay eggs, such as reptiles, birds, fish, and amphibians, have internal ears, which are not visible from the outside. They may have structures that look like ears, like the external openings of their auditory canals, but these are not true ears.
So, while there may be animals with visible ear-like structures on their eggs, these are not actually ears. They are part of the egg's structure and serve a different purpose.