Oospore

An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes.

[1] They are believed to have evolved either through the fusion of two species or the chemically induced stimulation of mycelia, leading to oospore formation.

[2] In Oomycetes, oospores can also result from asexual reproduction, by apomixis.

These haploid, non-motile spores are the site of meiosis and karyogamy in oomycetes.

[3] A dormant oospore, when observed under an electron microscope, has led researchers to draw conclusion that there is only a single central globule with other storage bodies surrounding it.