Experts have discovered 26 new species of worm from just one area of New Zealand, but say they are not surprised as they had perfect living conditions.
They were all discovered in an inlet close to the city of Porirua on the country's north island by a team from the National Institute of Water and Atmospheric Research (NIWA).
The scientists looked at the samples over a five-year period and found hundreds of examples.
NIWA marine biologist Dr Daniel Leduc said it was not a surprise to find new species as New Zealand worms haven't been studied for very long.
The 26 new worms, which had not been observed by scientists before, were all roundworms, also known as nematodes.
Roundworms are mostly about 1mm long and live in the soil or among sand grains on the beds of lakes and rivers or in the seabed, and some live as parasites in plants and animals.
Dr Leduc said they are one of the most successful groups of animals because they had adapted to live in many varying conditions.
Along with the new species, the scientists found another 29 nematode species in the inlet which were known but had not been found there before, or had not been found anywhere in New Zealand.
Dr Leduc said: "Most of us will think about fish and birds and cockles and snails and things that we can see with the naked eye, and we think that's it - that's all there is to the environment - but there's actually a whole other world in between the sand grains.
"The inlet is also subject to anthropogenic [human] impacts from land use changes and pollution, so a better knowledge of the nematode fauna will bring a more complete understanding of the value of this ecosystem and will facilitate monitoring in the future.
"We are still in the discovery phase for this group of animals, meaning we find species new to science pretty much everywhere we look.
"There are of course many more discoveries to be made in the country's other inlets and multitude of marine habitats.
"It's pretty easy to find new species in this country if you are ready to spend some time looking down a microscope."
