Tortoiseshell Tortoiseshell Tortoiseshell or tortoise shell is a material produced from the shells of the larger species of tortoise and turtle, mainly the hawksbill sea turtle, which is an endangered species largely because of its exploitation for the material. The large size, fine colour and unusual form of the hawksbill's scutes make it especially suitable. The distinctive patterning is referred to in names such as the tortoiseshell cat, several breeds of guinea pig, and the common names of several species of the butterfly genera "Nymphalis" and "Aglais", and some other uses. Tortoiseshell was widely used from ancient times in the West
Turtle shell before the carapace structure. Close examination of the partially formed carapace revealed similarity to the fully formed carapace in crown turtles such as the lack of intercostal muscles and limited rib mobility. Furthermore, it is made up of modified forms of laterally expanded and broadened ribs without ossification, similar in structure to the modern turtle embryo. The addition of South Africa’s 260-million-year-old Permian stem reptile "E. africanus", the hypothesized earliest stem turtle predating the "O. semitestacea" by 40 million years, revealed the early stages of carapace evolution. Histological data characterized "E. africanus" and "Proganochelys" ribs as homologous structures, both broadened