Examples of index fossils. Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
Methyl cellulose. Methyl cellulose (or methylcellulose) is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold (but not in hot) water, forming a clear viscous solution or gel.
The cellulose in plants is found in plant cell walls. Cellulose gives plant cells a rigid structure. This complex carbohydrate cannot be broken down by the human digestive system. Animals like horses and cows can break down cellulose with the help of symbiotic bacteria living in their digestive systems.