What's the plural form of onyx marble? Here's the word you're looking for.
Answer
The noun onyx marble can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be onyx marble.
However, in more specific contexts, the plural form can also be onyx marbles e.g. in reference to various types of onyx marbles
or a collection of onyx marbles.
