The cartilaginous form of a vertebral element, a skeletal element that forms around the notochord and is part of the vertebral column. [ http://orcid.org/0000-0002-6601-2165 http://purl.obolibrary.org/obo/go/references/0000034 http://dx.plos.org/10.1371/journal.pone.0051070 ]