It protects the spore from biotic (microbial, fungal viral), as well as abiotic (wind, heat, xeric conditions) factors.
They can lie dormant within the soil of a field for decades until the right conditions occur for viability (plant host present, rain, fire etc.).
[7] Resting spore formation plays an important role in the survival of diatoms through periods of adverse environmental conditions.
The thick silica frustule can also serve during period as a resting spore to enhance the resistance to zooplanktonic grazers,[8] which are known to be a frequently dominant source of mortality for many marine phytoplankton.
[9] Ultimately, the resting spore relies that it will be mixed back up to the surface at a time when conditions for growth are favorable and it can germinate.
Resting spores may allow diatoms to survive environmental variability from weekly and seasonal scale to decadal patterns like the NAO.
While from the standpoint of diatoms this is disadvantageous, it has been evidenced that rapid sinking and sedimentation of resting spores, particularly in large events after blooms, may represent an important export of nutrients to the deep ocean.
[15] Resting spores may be particularly important, because of their rapid sinking rate, which might reduce the opportunity for being recycled back into the food web of the photic zone.