The two species of Caloplaca, C. marina and C. maritima, are considered as marine lichens, since their natural habitat is near the sea. In the zonation usually considered, starting from the sea, there are the zone of Verrucaria mucosa, a litle above the zone of Verrucaria maura and after that a variety of lichens, including Xanthoria parietina, C. marina and sometimes also C. maritima. According to Irish lichens, C. marina is only found on hard coastal rocks and cement and C maritima can be found higher on the shoreline than C. marina and can extend slightly inland. Following the reference given above: (1) C. marina has a bright orange or yellowish-orange thallus, fragmented and granular or continuous and areolate, Well-developed specimens of can have pale prothallus and areoles with small lobes, and small grouped or scattered deeper-orange apothecia with thin, paler margins; (2) C. maritima has a yellowish areolate thallus with pale yellowish-white prothallus, and numerous waxy yellowish-orange or deep-yellow apothecia.