Wooden bowls

Hello,

We have some old wooden bowls that my husband's grandmother gave us and we would like to restore them. Both of the bowls very old (more than 80 years) and have water stains and scratches. They don't look like they have ever had a finish on them. They use to be used for making bread. Each bowl looks like it was made out of one solid piece of wood. Both bowls are rough and have stains and scratches. We would like to preserve the bowls for sentimental reasons. Could you please let me know what is the best way to remove the water stains, oil stains and scratches? And what type of protector should I put on the wood, so they will last another 100 years. Your help is greatly appreciated.