A grown-up giant tortoise can weigh up to 250 kilograms - heavier than three adults put together. Its shell is a big, smooth dome that can be as wide as a car tyre. The legs look almost like little elephant legs, with thick scaly skin. The neck is long, so the tortoise can stretch up to nibble leaves from low branches.
Giant tortoises live for an extremely long time. Many reach 100 years old, and some have lived past 150. One famous Aldabra tortoise called Jonathan, who lives on a different island (Saint Helena) is thought to be around 190 years old. That means he was already a grown-up tortoise when your great-great-grandparents were children.
Tortoises move slowly because they don't need to move fast. They have no predators on Aldabra and can find all the leaves and grass they need without rushing. On a hot afternoon, they often plop themselves into shallow muddy water to cool off, sometimes a dozen at a time in the same pool.
On Curieuse Island, near Praslin, there is a special tortoise sanctuary where visitors can walk among the giants. The tortoises are gentle and curious. They will sometimes stretch out their long necks to look at a person - just as curious about you as you are about them.