The protective structure where angiosperm eggs develop is called the ovule.

Here's a breakdown:

* Angiosperms: Flowering plants.

* Ovule: A small structure within the ovary of a flower that contains the egg cell (female gamete).

* Ovary: The swollen base of a pistil (female reproductive part of a flower) that encloses the ovules.

The ovule is protected by layers of tissue called integuments, which eventually develop into the seed coat after fertilization.