Block of material turned into a tree. (IMAGE) Elhuyar Fundazioa Caption Block of material turned into a tree. Credit UPNA/NUP-Public University of Navarre Usage Restrictions Credit must be given to the creator. License CC BY Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.