During times of environmental strain, such as extended droughts or heat waves, members of Spirogyra switch from asexual to sexual reproduction. Genetic material is exchanged via temporary conjugation tubes established between neighboring strands, or even cells from the same strand, forming an egg-shaped, orange zygospore. The cell wall of the zygospore is thick and adapted to surviving harsh conditions. The zygospore emerges as a new algal strand once the environment is more favorable.