What is a Site of Special Scientific Interest known for?

A Site of Special Scientific Interest (SSSI) is designated specifically for its unique natural features, such as its wildlife, plants, geological formations, or various ecosystems that hold significant ecological or scientific value. These sites are protected to conserve their biodiversity and natural habitats, ensuring that they remain intact for future generations to study and enjoy. The designation emphasizes the importance of these natural characteristics, which may include rare species, important habitats, or specific geological features that contribute to our understanding of the natural environment.

In contrast, the other options relate to areas that don't reflect the primary purpose of an SSSI. While architecture and historical significance can be important for cultural heritage, they do not pertain to the natural features that SSSIs aim to protect. Similarly, agricultural value focuses on the utility of land for farming rather than conservation of unique natural ecosystems.