I have a thing for chunky ammonites and find their inflated shapes very pleasing. This lovely has signs of intravital damage to the edge of her shell. We see similar signs of damage on the shells of modern Nautilus.
These lesions resemble frequently bitten edges. Perhaps damage from predation or the result of bashing up against something solid on the seafloor. There is a wee bit more damage on the mouth of the shell. Where the shell should have stopped growing upon the ammonite reaching puberty, the growth continues for another 5 cm of thinly laminated shell — perhaps signalling a shortage of resources for the ongoing construction of the usual thickness. Collection of the deeply awesome Emil Black.