Coral Files Used by Early Polynesian Settlers (image) PLOS Share Print E-Mail Caption This shows pristine (upper) and used (lower) surfaces of an Acropora coral file used to sculpt and smooth wood and shell surfaces. Credit Citation: Burley D, Weisler MI, Zhao J-x (2012) High Precision U/Th Dating of First Polynesian Settlement. PLoS ONE 7(11): e48769. doi:10.1371/ journal.pone.0048769 Usage Restrictions Credit required Share Print E-Mail 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.