Original Trezona Formation sponge reconstruction from our 2010 Nature Geosciences Paper (using pre-GIRI data). A flip card visualization of the data shows how serial imaging build up a 3D model whose layers can be traced and turned into the final 3D model of the sponge-like animal (color enhanced).

The Grinding Imaging and Reconstruction Instrument (GIRI) at the Princeton Grinder Lab originally was conceived when strange but ubiquitous two-dimensional fossil forms were found in approximately 640 million year old stromatolite reefs from the Trezona Formation in South Australia. The forms were thought to be part of larger three-dimensional objects, but could not be imaged via X-ray computed tomography scanning techniques due to the very weak density contrasts (both the fossils and matrix are made of calcite). Manual serial grinding and imaging of these Trezona objects led to the 3D reconstruction of sponge-like organisms suggested to be the oldest body fossil record of animals.