This information was published in 1966 in An Encyclopaedia of New Zealand, edited by A. H. McLintock. It has not been corrected and will not be updated.
Up-to-date information can be found elsewhere in Te Ara.
Fig. 16. Sponge spicules from the Oamaru diatomite. Some types of sponges contain a supporting skeleton of glassy spicules, common as fossils