Known as the ‘string-of-beads’ because of their appearance, these fossil organisms existed at the very dawn of life – and are the oldest fossils found in Tasmania. They have only been found in two other locations: Montana, in the United States of America, and Western Australia. The fossil’s scientific name is Horodyksia williamsii: after R.J. Horodyksia, who discovered the American specimens, and Ian R. Williams, the geologist who studied the Western Australian specimens. The excellent condition of these Tasmanian specimens means they may be the most significant finds of this fossil.

Simple analysis of these fossils is not possible, as there is no organic material associated with them; instead, they are found as moulds and casts in the sediments that enclose them. In Tasmania, this is dark, pyritic shale; in other locations, different sedimentary rocks yield the fossil.

With further discovery and study, string-of-beads fossils now meet most criteria to be generally accepted as having been formed from biologically living organisms. However, they are not listed in the hierarchy of living organisms as we know them – as plants and animals – rather, they have been temporarily placed among the very earliest forms of life that are comprised of cells.

These Tasmanian specimens were discovered in a rather unorthodox way. In 1995, Martin Laan found them in ancient rocks in the state’s Circular Head district. Not realising the scientific significance of the markings on the rocks, he incorporated several in a concrete floor in his home. In early 2006, Laan learned from geologist Clive Calver, of Mineral Resources Tasmania, of the Western Australian string-of-beads fossils. Laan’s flagstones were identified as bearing the same fossils and he, Calver and Western Australian researcher, Kathleen Grey, went on to publish the results in a scientific journal in 2010. That same year, Laan donated these specimens to TMAG’s geology collection.