Ponds usually have muddy or silty bottoms. If there are rocks and stones on the bottom, there is enough mud or silt to support pond plant roots. If a smaller body of water is too deep to be considered a pond but not large enough to be considered a lake, it is usually called a 'pool'. There are different kinds of ponds. There are 'permanent ponds' and 'vernal ponds'.
Permanent ponds are there all year round.
Vernal ponds exist only during a wet season, such as the spring or autumn. Vernal ponds dry up during the hot summer months. Vernal ponds have their own special animals and plants that come to life when the pond is full of water. When the water dries up, some plants and animals become 'dormant'. The tiny plants and the animals form protective coverings or burrow into the drying mud.