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Stones That Look Like Birds Eggs

Very few stones come out of the ground with the oval or round shape of bird's eggs. To achieve such a shape needs years of weathering, tumbling and wear and tear, usually in a body of moving water. Many eggs, which birds lay directly on the ground or on a beach, use their resemblance to stones, gravel and pebbles as camouflage. The shells of these eggs are brown, tan or reddish with spots, speckles or streaks.

Eggs that Mimic Nature
- Eggs that are more green or blue might be found among lichens or grass. The colors help protect the eggs from predators, though it also increases the risk of them being stepped on by mistake when the parents aren't guarding them. The colors are due to pigments inherited from the mother. Eggs often look like their natural surroundings and take on the appearance of rocks or other elements for protection.
Thorianite, Emus, Cassowaries and Others
- The Australian emu, the second largest bird on earth, lays an egg that begins as light green then darkens to green black, close to the color of thorianite, an important ore of uranium, or augite, a crystal found in volcanic rocks. The egg of the cassowary, another large bird from New Guinea with a kick that can disembowel a human being, is a gray-green, the same as olivine, or forsterite, a volcanic igneous rock found in the Red Sea, Germany, Arizona and Mt. Vesuvius. The eggs of the chicken, ostrich, duck, goose, Rufous hummingbird and others resemble the white of pure borax, pure white limestone or montmorillonite, a very soft rock that crumbles easily.
Gabbro and Shore Birds
- Gabbro, another igneous rock, is brown and black speckled and resembles the eggs of Wilson's phalarope, the arctic tern, the dunlin, the spotted and stilted sandpipers and the quail. All of these birds lay eggs in nests on the ground and their resemblance to stones helps protect them from predators.
Robin's Eggs and Aurichalcite
- Robin's eggs and the blue heron's eggs look like turquoise or aurichalcite. The tinamou, a large bird from Central and South America, lays its eggs in a ground nest of leaves and grass, and the eggs are brilliant green, like malachite, or even emerald.
Griquaite and the Aleutian Tern
- Griquaite resembles the reddish and black speckled egg of the Aleutian tern, the black-billed plover and the long-tailed jaeger. Griquaite is an igneous rock associated with the Kimberlite mines in South Africa. The freckled, reddish tan of the wild turkey's egg looks like the reddish version of lamprophyre and granophyre. Both of them are also igneous rocks. The former has no value and the latter is used as building stone or ornamental gravel.

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