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What is the purpose of the micropyle opening in a seed coat?

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Cluster of bright red seeds emerging from the cone-shaped fruit of a magnolia grandiflora, surrounded by large, glossy green leaves. — Seed Fruit and seeds of the southern magnolia (*Magnolia grandiflora*). The fruit is an aggregate of follicles, and each follicle bears a single red seed.

The micropyle is a minute opening in the integument of an ovule that often persists as a small pore in the seed coat, or testa.12

Its primary purpose relates to the reproductive process of flowering plants:

Fertilization: During double fertilization, the pollen tube grows toward the ovule and enters through the micropyle to deliver the generative nuclei (sperm cells) to the egg cell.23
Developmental Landmark: The egg cell is typically situated near this micropylar end of the ovule.23

While the micropyle serves as a critical gateway for fertilization, it is also a structural feature that remains visible on the surface of many mature seeds.2