Here's why:

* The process: Mineralization, the process of fossilization where organic material is replaced by minerals, requires a medium for the minerals to travel and interact with the organic material. Water is the most common and effective medium for this.

* Mineral transport: Water dissolves minerals from surrounding rocks and carries them to the organism's remains. This is essential for the replacement process.

* Chemical reactions: Water acts as a catalyst for chemical reactions that allow the dissolved minerals to react with the organic material, replacing it with mineral crystals.

* Permineralization: The most common type of fossilization, permineralization, relies on water carrying dissolved minerals into the pores and cavities of the organism's remains.

However, there are some exceptions:

* Very dry environments: Extremely dry conditions, like deserts, can sometimes lead to a form of fossilization called mummification. This involves dehydration and preservation of the organism's soft tissues without mineral replacement.

* Other liquids: While less common, other liquids like oil or even volcanic ash can facilitate some types of fossilization.

Ultimately, while water is the most common and essential medium for mineral fossilization, it's not the only one. There are other rare instances where other factors contribute to the preservation of organisms.