Category:Helcionelloida
Articles relating to the Helcionelloida, an extinct group of ancient molluscs (phylum Mollusca). These are the oldest known conchiferan molluscs, that is, they had a mineralised shell.
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Subcategories
This category has the following 4 subcategories, out of 4 total.
Pages in category "Helcionelloida"
The following 15 pages are in this category, out of 15 total. This list may not reflect recent changes.