Oxygen is able to support combustion. It is considered a very unique gas because it is able to support respiration in plants as well as animals.
As one of the most abundant elements on the planet, it is no surprise that 21% of the earth is made up of oxygen and the human body has around 65% of its mass made up of oxygen. Oxygen is essential for the life of animals and plants. Even fish and other underwater animals require oxygen and obtain their oxygen through the sources water provides.
Oxygen is one of the most unique gasses on the planet because it is so versatile. It is not only necessary for many things to live because it aids in respiration, but it is also essential for any type of combustion to occur. It is able to increase the combustibility of things and it is extremely combustible on its own.
Oxygen is more dense than air which allows it to survive in the environment. Due to the fact that water is partly made up of oxygen, this gas is soluble in water. It is a unique gas that is able to function in the air as well as in the water. It's properties do not change from dry air to water and it is able to function similarly.