A living creature that decomposes the remains of dead creatures into simple substances

The answer is: bacteria analyst

Bacteria are the most common organisms that break down the remains of dead creatures into simple substances. These microscopic organisms are found everywhere, from soil to the ocean, and break down organic matter such as dead plants and animals. Bacteria are essential to environmental health, because they help recycle nutrients and create new soil. Without it, the natural decomposition process will not occur. Bacteria break down the remains of dead creatures into simple substances, such as carbon dioxide, nitrogen and phosphorus, which are then used by other organisms. This process helps maintain balance in the environment and is an integral part of the food chain.