Common Tortoiseshell Limpet

Testudinalia testudinalis

Testudinalia testudinalis features a low domed shell that is oval in shape, typically measuring around 30 x 24 x 10 mm, although it can grow larger. The shell is characterized by fine radiating ridges and is banded with brown and white. This species is distinguished from others by its broad, oval foot and the presence of two sensory tentacles on its head, each with a tiny black eye at the base. It is commonly found on stones and boulders, particularly those covered in red crustose algae like Lithothamnion. This limpet inhabits northern regions of the Pacific and Northwest Atlantic Oceans, as well as European waters. It thrives in the neritic zone, typically at depths ranging from low water mark down to about 40 metres, although most occurrences are shallower than this. The common tortoiseshell limpet prefers rocky substrates, making it a typical sight for divers exploring these environments. Reproduction occurs in the spring when red eggs are laid in sheets. The larvae are planktonic, developing into trocophore larvae and later juvenile veligers before reaching maturity. Encounters with this species during dives are generally pleasant, as they can often be seen clinging to rocks, providing an interesting subject for underwater photography. The conservation status of this species is not evaluated, but it is recorded at numerous dive sites, indicating a relatively widespread presence.