Alchemical alterations to living things are difficult, but introducing creatures or plants to environments high in certain elements and/or compounds can cause them to adapt in useful if unpredictable ways.
For example, animals in especially salty water often develop to be able to efficiently remove excess salt from their bodies, but occasionally they will encorporate it with other elements or compounds to produce useful novel compounds not found in other forms of life. Creatures that deal often with fire may become resistant to it, or begin to use it themselves as a defense, or both.
Most creatures are already in contact with air, water, earth, and wood elements quite regularly, so it is the lack of these elements that causes novel adaptations.
Plants and animals in deserts of course adapt to either store water for long stretches (and produce toxins or other defenses to stop being eaten), collect water that might otherwise go to waste, or function with very little water for most of their lives. Burrowing and becoming more stony can also sometimes occur in order to both lessen the need for water and avoid temperature extremes.
There are other extremes that may even change the materials used by living creatures. For instance, many mollusks use limestone - a material made from a mix of earth, wood and salt elements - mixed with other compounds to form their shells. Some deep dwelling snails have found a way to incorporate iron (metal+fire) in a similar fashion in order to withstand the high heat of its volcanic home.
These are just examples from Bode, and so there are plenty of even more extreme examples on other worlds across the galaxy.
