Burgess Shale Worm
A fossilized Spartobranchus tenuis from the Burgess shale in Canada. The animal contains features of modern acorn worms and modern tube worms called pterobranches.
Spartobranchus tenuis
Spartobranchus tenuis in a tube. The worms look like modern free-living acorn worms, but resided in tubes. Modern mini-tube worms called pterobranches may have evolved from worms like this.
Acorn Worm
The modern acorn worm Harrimania planktophilus. The acorn worms are about 1.2 inches (32 millimeters) long when uncoiled.
Undescribed Acorn Worm
A modern-day acorn worm about 3.5 inches (88 mm) long.
Modern Pterobranch
A modern pterobranch, Rhabdopleura normani. Each of these tube-dwelling worms is only 0.02 inches (0.5 mm) long.
Modern Tubes
A modern tubular colony created by pterobranches. These tubes are similar to those seen fossilized in the Burgess shale.
Worms Illustrated
A reconstruction of Spartobranchus tenuis within and outside of their tubes.
Worm in Tube
A close-up of Spartobranchus tenuis in its tube.
Burgess Shale
The Burgess shale in Yoho National Park, British Columbia, where the Spartobranchus tenuis fossils are found.
Burgess Shale
Burgess shale quarries on Fossil Ridge in Yoho National Park.
Burgess Fossil Quarry
A close-up of a fossil quarry in the Burgess shale in Yoho National Park.
