Expanded Clay is created by heating marine clay to temperatures of 1150 degrees centigrade. Hence, these particles are essentially burnt clay with thousands of air-filled cavities. Expanded Clay is a natural products. It has sues in the construction industry as an aggregate, insulation in flooring and roofing and for drainage. Expanded Clay is an ideal horticultural aggregate since it has excellent ventilating properties. The cavities within the particles help retain water and prevent evaporation from the soil. It is chemically neutral, cleaner than soil and has pests of fungi.