Diapause egg or an embryonic resting stage in a life cycle is a dormancy strategy (similar to hibernation) implemented by some animal groups. This stage represents a period of delayed development, usually due to exposure to harsh environmental conditions such as temperature or nutrient changes. Resting-egg stage is quite common among the embryos of arthropods and fishes. Similarly, various groups of protists may produce a resting-cyst stage under adverse conditions.