Imagine, your job is to swim. Swim hard, and swim deep, all the way to the bottom of the ocean! You have to collect mollusk shells for your boss, bringing them up to be opened and hopefully, a pearl will be inside! Hopefully you will also make it back to the boat, or shore safely, but there are no promises. Luckily, now pearls are farmed, and people don't have to dive for mollusks in the same way anymore, but we still love and value the pearls they might contain just as much.
When I took this item, a massive mollusk shell containing several pearls, to show the children they all thought it 'mustn't be real'. Pearls are seen, much as they were in the past, as signs of wealth and importance, and the idea that anybody left a pearl, let alone more than one, inside its shell was odd to say the least. These pearls are not high quality though, so they were not harvested. No doubt there were other pearls in this shell once, which are probably now someones earrings or necklace!
Pearls are formed over a period of time by a mollusk, like an oyster or mussel. Any mollusk, even a snail can actually form a pearl, though for most it is very rare. Pearls can form in mollusks in fresh or salt-water mollusks (I think my shell is from a fresh water lake), and often fresh water pearls are cheaper. A pearl forms when the mollusk starts to protect itself from a piece of food or shell which has made its way inside its shell - something which shouldn't be there. Many people think that usually a pearl starts with a piece of sand, but this is very rare, most pearls start with some sort of organic material, often a parasite or an escaped piece of food. The 'foreign body' as this is called, irritates the mollusk and even tears off a bit of the mollusks outer skin, called the mantle layer. This surrounds the foreign body and begins to make nacre, also called mother of pearl. This is what it uses to repair its shell, and it is very hard. The mollusk builds layers of this nacre around the foreign body until it no longer irritates the mollusk. To learn more about how pearls are formed, click here. In the pearl exhibition of the virtual field museum, you can also see some of the ways pearls have been used throughout history. Click here to see this exhibition.
Although these pearls are a creamy pinky colour, pearls can come in all sorts of colours, from black all the way through to white. Although the mollusk still forms them the same way, with layers of nacre, pearls are 'farmed' by a method of seeding. They are opened by the 'pearl farmer' and a foreign body is actually inserted into the mollusk, to ensure it creates a pearl. The mollusks are then very carefully cared for, cleaned, kept as disease free as possible and in the best condition which can be achieved to ensure that the best pearls form. To learn more about seeding pearls, click here.
Sorry, if you were thinking of taking up eating oysters in the hopes of finding a beautiful pearl - you won't have much luck! The oysters we eat make pearls which look a bit like pebbles, the beautiful ones which we use to make jewellery come from very big, special breeds of oyster, and most of them aren't edible!