Registration Number M.138236
Phylum Mollusca
Class Gastropoda
Family Trochidae
| Scientific Name | Type Status |
| Cantharidus opalus (Martyn, 1784) | neotype |
| Limax opalus Martyn, 1784 | neotype |
| Trochus iris Gmelin, 1791 | neotype |
| Trochus acuminatus Perry, 1811 | neotype |
Common / Maori name marine snail, marine gastropod, sea snail, marine mollusc, top shell, opal top shell, Matango-ngore
Country collected New Zealand
Region collected North Island
Precise locality W of Matakaoa Point, Hicks Bay
Collected By Stewart, Andrew
Date collected 04 May 1992
Section Molluscs
The opal top shell has the distinction of being the first New Zealand animal to be scientifically recorded and illustrated. It was one of the species collected and taken back to Europe by members of the
Endeavour expedition. Although formally named in 1784 by the English naturalist Thomas Martyn in
The Universal Conchologist, the species had already been described and illustrated by the German naturalist J. E. Walch in the journal 'Der Naturforscher' (1774).
Cantharidus opalus is endemic to the New Zealand region, occurring on rocky ground off Three Kings, North, South, Stewart, Chatham, and Snares Islands. It lives and feeds on algae between low tide and about 27 metres depth.