SafePlants

Shell Lichen

Shell lichen is a common name applied to several lichen species. The text refers to multiple species, including Arthopyrenia plumbaria, Arthopyrenia cinchonae, and Arthopyrenia cinereopruinosa. It also mentions Thelidium litorale, Coccocarpia palmicola (Salted Shell Lichen), and Hollow shell lichen (NB. Acrocordia gemmata. Acrocordie bulbifre. Bud-bearing shell lichen).

Taxonomy and Nomenclature

• Kingdom: Plantae (in reference to lichens generally)
• Genus: Arthopyrenia, Thelidium, Coccocarpia, Acrocordia, and others.
• Family: Arthopyreniaceae, Monoblastiaceae (for Hollow shell lichen)

Distribution and Habitat

Shell lichens can be found in various environments, including:

• Marine intertidal zones, growing on shells.
• Allegany Co., Maryland.
• Scottish Highlands.
• Canary Islands.

Morphological Characteristics and Growth Habits

• Shell lichens are described as small, shell-like organisms.
• Some species are crusty and grow on rocks.
• Collemopsidium foveolatum is described as black, flattened to moderately convex, immersed in pits in shells and softer rocks, and measures 0.10–0.24 mm in diameter.

Interactions with Other Organisms

• Snails graze on shell lichens, sometimes applying the lichen material to their own shells.
• Crabs may have pink spots that are actually lichen.
• Limpets can have the black lichen, Verrucaria mucosa, growing on their shell.

Quirky Facts

• Some snails actively "paint" their shells with lichen material as a form of camouflage or decoration.
• Shell lichens are pioneers of life on rocks, eventually being replaced by leafy and bushy lichens over time (potentially taking 5 years or more).