New Zealand screw shell (Maoricolpus roseus)

What to look for

  • Smooth conical shell.
  • Generally brown, fading to purple/white with age.
  • Broader tapering shell with up to 18 whorls.
  • Grows to 9 cm long, usually ~6 cm long.


  • Lying on or partially buried in sand, mud or gravel.
  • Also found in crevices.
  • Low intertidal & subtidal up to 130m depth.


  • Densely blankets the sea floor with live & dead shells.
  • Can compete with scallops & commercially farmed shellfish for food.

Current locations 

  • South east to north-east coast Tasmania
  • Bass Strait
  • Wilson's Promontory Victoria & north to Botany Bay NSW

What you can do

  • Inspect & clean niche areas & antifoul your vessels regularly.
  • Clean & dry equipment before transporting & using in a different location.  

More information

More information on this pest can be found on the National Introduced Marine Pest Information System

Report a sighting

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