Tortoises or Land Turtles are land-dwelling reptiles of the family of Testudinidae, order Testudines. Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. Tortoises can vary in size from a few centimeters to two meters.
Female tortoises dig nesting burrows in which they lay from one to thirty eggs. Egg laying typically occurs at night, after which the mother tortoise covers her clutch with sand, soil, and organic material. The eggs are left unattended, and take from 60 to 120 days to incubate.The size of the egg depends on the size of the mother. Upon completion of the incubation period, a fully-formed hatchling uses an egg tooth to break out of its shell. It digs to the surface of the nest and begins a life of survival on its own. Hatchlings are born with an embryonic egg sac which serves as a source of nutrition for the first 3 to 7 days until they have the strength and mobility to find food.
Source: en.wikipedia.org/wiki/Tortoise - 01.04.2010
Image an elastic, agile cat besides this Land Turtle, then it comes clear, that it is not important "the more robust the better" nor "the more agil the better", but each creature has its environment, for which it is perfectly provided.