Newfoundland's Thrombolite Walking Trail: walking past 600-million-year-old microbial fossils
Newfoundland's northern coast is a peninsula that takes the full force of North Atlantic winter winds. Just north of the village of Flowers Cove, Atlas Obscura has profiled a short coastal path called the Thrombolite Walking Trail. The route runs past what look like scattered, weathered boulders, but which are in fact one of the rarest categories of fossil rock on Earth.
The rocks are thrombolites, a microbial limestone known to palaeobiologists. Unlike their more familiar cousins, stromatolites, thrombolites do not display the characteristic horizontal banding; they look clotted or blistered. Only about ten sites worldwide are known. Memorial University of Newfoundland dates the Flowers Cove site to roughly 600 million years.
That age places the rocks in the Ediacaran period, the geological window that immediately precedes the rise of complex multicellular life. The cyanobacterial colonies that built the thrombolites lived in shallow seawater; their structures represent the last great phase of microbial dominance before the appearance of animals.
The Flowers Cove site was introduced to scientific literature in 1992 by Memorial University palaeontologists. Local residents had been aware of the rocks for far longer; in regional usage they were called "magnet stones" or, less reverently, "angels' skulls." Atlas Obscura quotes from an 1880s fisherman's journal recording the unusual stones, confirming that the structures were familiar in the 19th century.
The trail itself is short: about 750 metres. Timber platforms have been installed along certain stretches so that visitors do not step directly on the thrombolites. A small interpretive centre, built in 1999, sits just south of the trail head. It is operated by the Newfoundland Heritage Foundation and opens from May to September.
Living thrombolites are known today at only three locations: Lake Clifton in Western Australia, Highborne Cay in the Bahamas, and the Cay Sal Bank in the Caribbean. The Newfoundland structures are classed as fossil — far beyond their active growth phase — but their morphology and internal structure remain critical reference material for comparison with the modern sites.
Professor Liz Hayes of Memorial University wrote in a 2018 paper that "the Flowers Cove exposure is one of three sites worldwide that allows us to reconstruct shallow-marine Ediacaran conditions." Hayes noted that in the last five years the site has become "a recognised stop on international geology itineraries."
Access to the site is via Route 430, about three hours' drive from the port of St. Anthony. The provincial tourism office reports that the site received about 18,000 visitors in the 2025 season, roughly three times its 2010 figure. The growth has been driven in particular by European scientific tourists.
The interpretive centre's display visualises the established model of thrombolite formation: build-up by mat-forming algae and cyanobacterial colonies fixed to a shallow seabed substrate. The lumpy appearance of the domes is a direct expression of the colonies' growth pattern.
The Flowers Cove community has folded the site into its own historical narrative. From fourth grade, the village's school children learn about the thrombolites as a piece of global heritage within their own coastline. Atlas Obscura notes that the most recent of the village's annual "fossil walks" drew over 600 residents and visitors.