The koru is the Māori name given to the new unfurling fern frond and symbolizes new life, growth, strength and peace. It is an integral symbol in Māori carving and tattoos.
Koru can also refer to bone carvings. Those generally take the shape of the uncurling fern plant. When bone is worn on the skin, it changes colour as oil is absorbed. The Māori took this to symbolise that the spirit of the person was inhabiting the pendant. When someone gives a pendant to someone else, it is the custom that they wear it for a time so that part of their spirit is given as well. (Full article...)