Chelonia is a taxonomic order of reptiles that includes turtles, tortoises, and terrapins. These animals are characterized by their unique shells, which consist of a dorsal carapace and a ventral plastron. Chelonia are found in many different environments, including oceans, rivers, lakes, and on land. They are ectothermic, meaning that their body temperature is regulated by their environment, and they are oviparous, meaning that they lay eggs to reproduce. Chelonia are a diverse group of animals that have been around for millions of years and have adapted to many different ecological niches.