3d image of norcholestane skeletal formula

norcholestane 24-norcholestane steroid derivative biomarker oleanane diatom sediment environment evolution dinoflagellates thalassiosira measurement gas chromatography-mass spectrometry marine fossils rendering substance matter material compound component agent stuff reagent functional group precursor synthesis reaction production building block bioactive cell biochemistry biology biomolecule molecule molecular formula skeletal structural structure ball stick chemistry chemical science scientific research organic