Abby Smith

22 Abby Smith

Scientist

Discovery is one of the great joys of science, and what could be more exciting than digging up a fossil that tells you something about the long-dead past? Fossils are usually bones or shells, but I spend days peering at remnant crumbs of bryozoans that once covered the seafloor. Bryozoans are tiny animals that build their skeletons together in colonies. They make complex structures out of repeated modules, the same way that repeating knitted stitches makes a sock. Look at any stone wall in Oamaru (Whitestone City) and you’ll see tiny broken branches and crusts of bryozoans that once thrived in warm shallow water on the Waitaki coastline. It’s amazing to think that animals less than a millimetre across have produced whole quarries of limestone! New Zealand had a diverse and abundant bryozoan fauna 35 million years ago, and it does now too. My research group studies living bryozoans alongside the fossils to discover what they can tell us about the past.

Bryozoans: The tiny critters that made enough limestone for a city

Scale = mm

Odontionella cyclops St Lukes, Oamaru

Tiny bryozoans band together to build a robust colony called Odontionella cyclops, a glob about the size of a marble, living on the seafloor. When magnified, you can see each contributor is a little box with a big opening for their tentacles to come out and feed, and a protective frontal shield with a spine. Millions of bryozoans, long dead and broken up, make up the local limestone known as Oamaru Stone, from which this church, and many other buildings, were constructed (it’s also the white stone on the Dunedin Railway Station).