Orthogonium
Orthogonium is an Ediacaran fossil genus that lived about 550–530 million years ago. It has only one known species, Orthogonium parallelum. The fossil shows eight parallel rows of square tubes lying flat in the rock. The tubes reach up to 58 mm in length and are divided into 28 sections; each section is about 2 mm high and 3 mm wide, with grooves between sections. The square tubes may be original hollow structures that kept their shape during fossilization and were filled with sediment.
The fossil looks similar to other Ediacaran life forms and to crinoid arms, a comparison noted by Gürich who likened it to Ectenocrinus simplex. Fedonkin described it as a quilted petalonam, and Sepkoski placed it with Medusae. Only one species is known: O. parallelum. It was found in 1930 by Georg Gürich in the Kuibis Quartzite, Nama Group, Namibia, in rocks that record a tidal environment—alluvial plains with channels and deltas, overlain by offshore shales. Radiometric dating places it at about 530 ± 10 million years old.
Because its exact classification is debated—crinoid, jellyfish, or something else—its life habits remain uncertain.
This page was last edited on 3 February 2026, at 15:12 (CET).