Tooth creation starts at the slightly bifid, white, inner end of the semi-translucent radular sac (1) with secretion of colourless transparent cuticular material by odontoblast cells. As each new tooth commences, the previous one is pushed forwards along the sac. Cells along the roof of the sac (2) make incremental additions, including the hardening salts of iron and silicon, to the teeth as they travel along the sac, with a progressive change from colourless through darkening shades of yellow/orange visible through the translucent sac walls. Creation is complete by the time the tooth reaches the buccal cavity, where the radula emerges from the radular sac (3) and widens into a hyaline shield (4).
Concise
Part 1, SHELL FORMS: 02 Patella pellucida. Growth Stage 2 (GS2). July 2012. Littoral. North Yorkshire, England. © P. Lightfoot.
Part 2, BODY & ANATOMY: 03 Patella pellucida. Growth Stage 3 (GS3). 2009. Sublittoral, Farne Islands, Northumberland, England. © P.Lightfoot.
Part, 3 HABITS & ECOLOGY: 04 Patella pellucida. Length 4.6mm. Growth Stage 3 (GS3). September 2016. Yorkshire, England. © P.Lightfoot.