Collared Mosscap vs common grey sea slug

Rickenella swartzii compared with Aeolidia papillosa

Taxonomic Classification

Rank	Collared Mosscap	common grey sea slug
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Basidiomycota (Club Fungi)	Mollusca (Mollusks)
Class	Agaricomycetes (Mushrooms)	Gastropoda (Gastropoda)
Order	Hymenochaetales (Hymenochaetales)	Nudibranchia (Nudibranchia)
Family	Rickenellaceae	Aeolidiidae
Genus	Rickenella	Aeolidia
Species	Rickenella swartzii	Aeolidia papillosa

Conservation Status

Collared Mosscap

LC — Least Concern

common grey sea slug

LC — Least Concern

Physical Characteristics

Attribute	Collared Mosscap	common grey sea slug
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Collared Mosscap

Habitat

Typically found in forest floors, decomposing wood, and soil ecosystems.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

common grey sea slug

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Belgium, Chile, Denmark, Norway, and Sweden.

Collared Mosscap

The Collared Mosscap, known scientifically as <em>Rickenella swartzii</em>, is a small fungus belonging to the family Repetobasidiaceae within the order Agaricales. <em>Rickenella swartzii</em> is characterised by its diminutive fruiting bodies, which typically feature a small, convex to umbilicate cap and a slender stipe. The species typically grows in mossy substrates, on forest floors, decomposing wood, and soil, where it plays a role in nutrient cycling as a saprotrophic or potentially mycorrhizal organism. It is reported to occur in Belgium, Denmark, Norway, and Sweden, reflecting a distribution across parts of northern Europe. Detailed biological traits including typical lifespan measures and physical dimensions are poorly documented for this fungal species in available literature. The Collared Mosscap is currently assessed as Least Concern on the IUCN Red List, indicating that it is not considered to be at significant risk of global population decline.

common grey sea slug

<em>Aeolidia papillosa</em>, commonly known as the common grey sea slug, is a nudibranch mollusc belonging to the genus Aeolidia within the family Aeolidiidae. Despite the species name referencing terrestrial and aquatic habitats including forests and freshwater, <em>Aeolidia papillosa</em> is primarily a marine organism. Its range includes Belgium, Chile, Denmark, Norway, and Sweden, indicating a distribution across the North Atlantic and into South American waters. Common grey sea slug is assessed as Least Concern on the IUCN Red List. The species is typically found in intertidal and subtidal zones, where it preys on sea anemones and stores stinging cells from its prey in its dorsal cerata for defense. Biological traits of this species remain poorly documented in the scientific literature.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden