Salamanders

Limb regeneration
http://www.laboratoryequipment.com/news-Salamanders-Could-Help-Fight-Degenerative-Diseases-121611.aspx?xmlmenuid=51

Immune system
http://www.33rdsquare.com/2013/05/salamander-macrophages-found-to-be-key.html#.UZ4NIAy4LJo.facebook