Some archaeal cells, like this Haloferax gibbonsii, contain many small granules. We do not yet know what they store, but based on their electron density (how dark they appear in EM images), it may be a carbon source.
Archaea also use storage granules, and you will see many examples throughout the book. Compared to the relatively smooth surface of bacterial granules, the edges of some archaeal granules are spikier, giving them a rougher appearance, as in this Halorubrum litoreum cell. Others are smooth and, just like in bacteria, they exhibit a range of morphologies depending on what they store. For instance, compare the granules in the Learn More section (⇩).
Some archaeal cells, like this Haloferax gibbonsii, contain many small granules. We do not yet know what they store, but based on their electron density (how dark they appear in EM images), it may be a carbon source.
This Halohasta litchfieldiae cell has more unusual granules. The high electron density (darkness) of these punctate structures suggests that they are iron storage granules, known as ferrosomes.