Fibropapillomatosis is a benign tumour disease of marine turtles, predominantly in the green sea turtle, "Chelonia mydas", but it has also been reported in the loggerhead sea turtle "Caretta caretta", olive ridley "Lepidochelys olivacea", Kemp's ridley "Lepidochelys kempii", and leatherbacks "Dermochelys coriacea". This neoplastic disease causes proliferation of papillary cells (hyperplasia) and gives rise to excess fibrous connective tissue in both epidermal and dermal skin layers – or more specifically, proliferation of dermal fibroblasts and epidermal keratinocytes. This causes tumorigenesis in sizes less than 1 cm up to more than 30 cm in diameter.