The Precambrian-Cambrian transition is a mysterious period when life exploded and significant environment changes happened (e.g., oxygenation, intensive tectonic activities). The silicon (Si) world may have also changed due to the appearance of siliceous sponges, which seem to be the first organisms to utilize Si to build skeletons. How can they affect Si cycle?  How is Si cycle related to other geological processes (e.g., weathering and reverse weathering)? How could Si fluctuations influence life transition? I'm interested in uncovering clues to these questions.