See also: Ammonitella
ammonitella (plural ammonitellas)
- The initial part of a spiral shell, originating from a central chamber, in ammonoid molluscs
2016 January 14, “Paleobiology of the Latest Tithonian (Late Jurassic) Ammonite Salinites grossicostatum Inferred from Internal and External Shell Parameters”, in PLOS ONE, DOI:10.1371/journal.pone.0145865:
- The embryonic stage, consisting of a small ellipsoid protoconch and ammonitella, ends at about 0.6 mm.