What are the ammonite's radial ribs like?
- The ammonite's shell is packed with strong radial ribs that branch before crossing over the venter.
- The radial ribs are strong but very faint.
- The ammonite has big radial ribs on the half of the shell closer to the venter, but they become fainter as they approach the umbilicus.
- The ammonite is packed with thin, fine, radial ribs.
