Definition
An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes. Think of it as a fungal 'seed' resulting from sexual reproduction! Unlike asexual spores, it's the product of two parents combining their genetic material. This creates genetic diversity. Oospores are resistant to harsh conditions and can survive for long periods. They germinate when conditions are favorable. They're a key part of the life cycle for certain organisms.