This sculpture has a UV resistant, non-yellowing Acrylic Urethane to guarantee preservation of the color. It is similar to automotive clear coat, but formulated for wood. 
 
This sculpture is part of a very successful series I've been making for several years. To me, they represent earth, fire, and water. Banksia Seeds do not germinate until they've been through fire (process called stratification). The lighter colored edge of the burl bordering the epoxy hints at a coastline against a body of water, with pulverized mica has being added to help with that effect. The burl woods represent earth. 
Neither wood species are endangered. Both are very hard and heavy. Natural colors. The Red Mallee is a popular garden variety shrub in Australia.