The nose helps us a lot. It tells us when dinner is almost ready and leads the way to sweet cakes. It also tells us to keep away from bad smells. But do you know the interesting facts about something that smells bad?

Fish

You might have noticed that fish smell unpleasant sometimes. Fish from the ocean smell the strongest. These saltwater fish have a chemical (化学物质) called TMAO. While we prepare fish for cooking, TMAO is already changing into other things. One is called TMA. It smells super smelly. Usually, before cooks make saltwater fish a dish, they wash fish. And most of the TMA can be washed away. Cooks also add lemon to make the fish less smelly.

Feet

Foot sweat (脚汗) itself does not have a bad smell at first. But it has food and water that the bacteria (细菌) need. With them, the bacteria give off some smell. Most shoes often keep sweat in them. That makes shoes and socks warm and wet—a place where bacteria can grow. Different types of bacteria give off different smells. That's why feet may smell like bad vegetables, smelly eggs or other smelly things.

Eggs

Many things smell terrible when they go bad. But a bad egg gives off the most famous bad smell of all and draws people's attention. When an egg goes bad, the bacteria help to change the sulfur (硫) in its white part into sulfur and hydrogen (硫化氢). And it smells really bad. The nose just warns us away from it because too much sulfur and hydrogen will harm our health.