The world's oldest oceanic island group, there is literally nowhere else like Seychelles; its long isolation has resulted in high levels of endemicity found in few other places. The contrast between these ancient granitic inner islands and the far younger atolls of the Aldabra group is striking; here, the tropical forests and mountains of the granitics are replaced by dry, flat razor-sharp rock formations. Only the hardiest can survive here, such as the Aldabra giant tortoises; found nowhere else and in huge numbers. they have literally engineered the ecology of the island to suit their needs.