Hydra is a genus of simple fresh-water animal. They can be found in most lakes and ponds but are only a few millimeters long (think along the lines of Greek mythology but not nearly as scary).
Surprisingly, during regeneration few new cells are formed! During this process, which is called morphallaxis, the existing tissue is merely remodeled to form a smaller version of the original parent organism. Once this activity is completed, the newly formed organisms will then be able to grow to a normal adult size.
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