When young, the organism is solid but as it matures it becomes hollow and somewhat convoluted and has the appearance of a small leathery brown bag about the same size as a tennis ball.

Young individuals can resemble other globular forms of algae, such as Soranthera ulvoidea.

Leathesia will break apart into filaments whereas other globular forms will flatten but remain intact.

[6] Myrionema papilosum Myractula clandestina Elachista fucicola Striaria attenuata Litosiphon laminariae Elachista flaccida Elachista scutulata Punctaria latifolia Asperococcus bullosus Ulonema rhizophorum Myrionema strangulans Ddictyosiphon foeniculaceus Chordaria flagelliformis Soranthera ulvoidea Corynophlaea crispa Leathesia difformis (L. marina) According to WoRMS (October 2023):[7] Chapman, A.R.O.

"Demographic study of the macrothallus of Leathesia difformis (Phaeophyta) in Nova Scotia".