Porella is a difficult bryozoan genus. Many of the species are relatively similar, and in many cases, you must get down to a microscopic level to tell them apart. The genus is characterized by the presence of a lyrula, but this could sometimes be small/missing. The genus also has a suboral avicularium, which sometimes is partly hidden. Only marginal pores are found in Porella species, and is one of the main features used to distinguish Porella from genera like Smittina.
There is one species of Porella that has a feature that makes the species "easier" to identify, and that is Porella struma. It has a distinct, large avicularium, and in addition to the size, how the avicularium beneath the mandible looks is also different from the other species. In addition to a horizontal crossbar, there are also two smaller vertical struts. These are not found in the other Porella species currently present here.
