Casu Marzu is a traditional Sardinian sheep milk cheese that is notable for being one of the world's oldest and most unusual cheeses due to its method of production and consumption. Here are some key points about Casu Marzu:

1. Production: It's made from sheep's milk that is allowed to ferment and become infested with live maggot larvae ( maggots).

2. Maggots: These larvae, which are naturally present in the environment, consume parts of the cheese, breaking down its fats and creating a distinctive texture and flavor.

3. Texture: The presence of live maggots makes the cheese very soft, almost runny. When the maggots are removed or die off, the cheese becomes firmer.

4. Safety: Consumption of live maggots was considered safe traditionally, but recent concerns have led to bans in some countries.

5. Legal status: In the European Union, it's illegal to sell Casu Marzu due to health regulations. However, possession and private consumption may still be permitted in Sardinia.

6. Cultural significance: It's an important part of Sardinian culinary heritage and is often served at special occasions.

7. Flavor: Described as very strong and pungent, with a unique, creamy consistency.

8. Preservation: The cheese is preserved under muslin cloth, allowing flies to lay eggs in the cheese.

9. Controversy: Some consider it a delicacy, while others view it as unsafe or unethical.

10. Variants: There are similar cheeses in other cultures, such as Casu Festu in Sardinia and Mimolette in France, though these don't involve live maggots at the time of consumption.

Casu Marzu remains a controversial and highly debated food item, primarily consumed in Sardinia despite legal restrictions in many places.