What is the primary feature of a spore?

The primary feature of a spore is that it has a thick shell-like wall, which is essential for its survival in harsh environments. This protective layer provides durability and resistance against extreme temperatures, desiccation, and harmful chemicals. The thick wall encases the spore's genetic material, allowing it to remain dormant until conditions become favorable for germination and growth. This feature distinguishes spores from other reproductive structures, emphasizing their role in ecosystem resilience and propagation under adverse conditions.

The other characteristics listed do not fully capture the essence of what defines a spore. For instance, while spores can serve a reproductive function, they are more than just reproductive structures due to their protective qualities and ability to endure unfavorable conditions.