snails.

Land snails are among the oldest and most diverse animal groups on earth, with a fossil record stretching back over 500 million years. There are an estimated 40,000 to 60,000 known species of land snail, inhabiting every terrestrial environment from tropical rainforest to high-altitude alpine meadow to desert.

Their shells — grown continuously throughout their lives from calcium carbonate secreted by the mantle — are among the most structurally efficient natural materials known, providing protection while remaining light enough to carry indefinitely. Snails navigate using a combination of chemical sensing, photoreception, and memory for routes previously traveled. They are solitary, slow, and extraordinarily resilient — surviving conditions that end faster animals.

Land snails hold the unfortunate distinction of having more documented extinctions than any other animal group in recorded history.