Common Limpet

• Its radular teeth, reinforced with goethite fibres, are the strongest biological material in tension ever measured, ahead of spider silk.
• It practises homing: it wears a scar into the rock that matches the rim of its shell exactly, and always returns to the same spot after feeding.
• By grazing it stops algae from colonising the rock, which shapes the whole intertidal community.
• It always returns to its spot. Each limpet has a home scar of its own, a depression it wears into the rock itself that fits the edge of its shell exactly; it goes out to graze at high tide and returns to that precise point by following its own mucus trail.
• That perfect fit is what lets it seal the shell against the rock and avoid drying out through hours of low tide.
• Its teeth are the toughest biological material known. A 2015 study measured a tensile strength of between 3 and 6.5 gigapascals in the teeth of its radula, higher than spider silk and comparable to the best carbon fibres. They are made of goethite nanofibres embedded in chitin.
• With them it scrapes microscopic algae straight off the stone, wearing the rock away in the process: limpet grazing is a measurable agent of erosion on rocky coasts.
• It changes sex: it matures as a male, and a proportion of individuals become female with age.
• It can live twenty years on the same rock.

Skeleton type

Invertebrate - external calcareous shell (mollusc)

Habitat & environment

Intertidal rocks of the north-eastern Atlantic

Sources consulted: https://es.wikipedia.org/wiki/Patella_vulgata