I am a desert that is known for its unique and diverse ecosystem, including a large population of endemic succulents and cacti. My climate is characterized by extreme temperatures, with hot, dry summers and cold, wet winters. The specific region is also known for its rich biodiversity, with many rare and endangered species. Additionally, I’m home to the world's largest single-celled organism, which is visible to the naked eye. What desert am I?

1. I am located in a region that is known for its Nama people.
2. I experience a unique phenomenon known as 'fog basking' by some of my fauna.
3. I am one of the oldest deserts in the world, with unique geological features.
4. I have landscapes with sand dunes, gravel plains, and rocky mountains.