The basic shape of a penny bank was the mother’s breast. In the ancient Greek culture this was a symbol of prosperity and fertility. This basic penny bank model was found in excavations all over Europe. Potters introduced this easy to produce shape in the Middle Ages (12-14th century).
The oldest (13th century; amongst experts disputable!) European piggy bank was found in Billeben (Thüringen, Germany). Certain is that potters from the 17th century on produced clay money banks (also) in the shape of animals like a pig. Other craftsmen started to produce them in tin, metal, silver, etc. The industrial production of ceramic piggy banks, with moulds, started approximately in the middle of the 19th century.
From medieval times on a large wooden heavy sacrifice coffin stood in the church porch. With a slot in which the faithful were expected to put their sacrifice, a donation in coins. These coffins were often found empty because others could not stay away with their sticky fingers. They put a glue stick (used in other occasions to catch singing birds) through the slot and coins remained on the stick.
A similar method can also be applied to your piggy bank. Grab a large knife and insert it into the slot while you keep the piggy bank upside down. Shake a little and the coins will slide along the knife out of the pig. Don’t ever put paper money in your piggy bank. If you are able to get it out, it will mostly be in pieces.
In the early centuries people did indeed break their piggy banks and threw the fragments in the cess pool. To find out what form an early piggy bank has, research on fragments is helpful.