What type of fossil is formed when silica is added?

When silica is added to organic material, it can lead to the formation of a type of fossil called a siliceous fossil. This process typically occurs through permineralization, where silica replaces the original organic material, preserving its structure in a durable form. Common examples include opal and certain types of diatoms, which are microscopic algae that can form intricate siliceous shells. These fossils can provide valuable information about past ecosystems and environmental conditions.