Shuhai Xiao (IMAGE) Virginia Tech Caption Virginia Tech geobiologist Shuhai Xiao and collaborators reported a 550 million-year-old sea sponge fossil, filling in a gap in the evolutionary family tree of one of the earliest animals. Photo by Spencer Coppage for Virginia Tech. Credit Photo by Spencer Coppage for Virginia Tech. Usage Restrictions Photo by Spencer Coppage for Virginia Tech. License Original content 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.