The mid-Ordovician saw the main cephalopods with septa solid ample to cope While using the pressures linked to deeper h2o, and could inhabit depths larger than 100200 m.[139] The way of shell coiling would demonstrate to be important to the future results from the lineages; endogastric coiling would only allow big sizing to become attained which has a straight shell, whereas exogastric coiling to here begin with instead