common grey sea slug vs Common Rustgill

Aeolidia papillosa compared with Gymnopilus penetrans

Taxonomic Classification

Rank	common grey sea slug	Common Rustgill
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Mollusca (Mollusks)	Basidiomycota (Club Fungi)
Class	Gastropoda (Gastropoda)	Agaricomycetes (Mushrooms)
Order	Nudibranchia (Nudibranchia)	Agaricales (Gilled Mushrooms)
Family	Aeolidiidae	Hymenogastraceae
Genus	Aeolidia	Gymnopilus
Species	Aeolidia papillosa	Gymnopilus penetrans

Conservation Status

common grey sea slug

LC — Least Concern

Common Rustgill

LC — Least Concern

Physical Characteristics

Attribute	common grey sea slug	Common Rustgill
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

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.

Common Rustgill

Habitat

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

Range

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

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.

Common Rustgill

<em>Gymnopilus penetrans</em>, the common rustgill, is a saprotrophic basidiomycete fungus in the family Hymenogastraceae, commonly found across temperate regions of Europe and beyond. It has been recorded in Belgium, Denmark, Norway, Portugal, and Sweden, typically fruiting on decaying conifer wood, stumps, buried roots, and woody debris in forests and woodland habitats. The fruiting bodies are small to medium-sized mushrooms with tawny orange to rust-brown caps, typically 2–7 centimeters in diameter, and bright rusty-orange gills that give the species its common name. The stem is similarly colored and typically fibrous. As a wood-decaying fungus, common rustgill plays an important ecological role in the decomposition of dead conifer timber and the recycling of nutrients in forest ecosystems. The species produces minute, roughened, rusty-brown spores. It is assessed as Least Concern on the IUCN Red List. The common rustgill typically fruits from late summer through autumn. It may occasionally be confused with related <em>Gymnopilus</em> species; some members of the genus contain potentially toxic or psychoactive compounds, though <em>G. penetrans</em> is generally considered of low toxicity. Biological traits such as average lifespan and detailed dietary substrate specificity remain poorly documented in comprehensive ecological databases.

Shared Countries

Both species can be found in 4 countries:

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