Egg laying is common, not universal
Most living reptiles lay eggs, a reproductive mode called oviparity. Turtles, crocodilians, tuatara, and most lizards and snakes are oviparous. Some lizards and snakes retain embryos inside the body and give live birth. The diversity of reptile reproduction is one reason that broad claims about a single “reptile egg” often fail.
Eggs and nests vary by species
Reptile eggs may have flexible, leathery shells or more rigid, calcified shells. Females may bury eggs in soil, use decaying vegetation, attach them to protected surfaces, or guard a nest. Crocodilians are notable for building and protecting nests, whereas many other reptiles leave eggs after laying. Nest placement affects temperature, moisture, gas exchange, and exposure to predators.
Incubation is not a fixed countdown
Development time depends on species and environmental conditions. Temperature can influence the speed of development, and in some reptiles it also influences the sex of hatchlings. It does not do so in every species. Hatchlings use an egg tooth or similar temporary structure to break the shell. Wild nests should be left undisturbed unless work is being done by authorized conservation professionals.
