The defining characteristic of objects made with the clay known as porcelain are their hardness and translucency (when made thinly).
It had begun to be developed in China from porcelain-like clays as early as the Shang Dynasty (1600 – 1046 BC) but wares became highly prized and exported as ‘porcelain’ in the Han Dynasty.

Although in Europe the name porcelain came to be used, it was also referred to as ‘China’ reflecting the origin of the wares.
It was not until 1712 that a French Jesuit father gained access to the secret ingredients of the clay and the door was open for European production on a grand scale.

For MORE on porcelain this is a good place to start.

Porcelain was thought to resemble the cowrie shell which shares qualities of fineness and translucency.

Those illustrated are known as the European cowrie (Trivia monacha) and were gathered many years ago from the beach at Llanddwyn Island, Anglesey, Wales.  They are shells of a small sea snail, or marine gastropod mollusc, of the family Triviidae (Trivia meaning common, and monacha meaning ‘solitary’).

In Wales they are known as cowries but in some parts of Scotland they are called ‘groatie buckies’ (maybe porcelain would have been called something else if named after those!).