One of the most commonly studied features of the features in organic geochemistry are biomarkers, which are organic molecules that can be detected in the geosphere, which have enough structural information that they can be used to indicate the existence of present and past forms of life. Below are two examples of hydrocarbon biomarkers. Cholestane (left) and hopane (right) that diagnostic of eukaryotes and bacteria, respectively.
The movie below provides an example of how we can visualize the mix of hydrocarbon biomarkers extracted from a rock. Each peak in this multidimensional gas chromatogram is a unique organic compound.