Radula under high magnification of Scanning Electron Microscope (SEM). Barents Sea, Arctic. © B. Sirenko.
1000μm = 1 mm
The major (second) lateral tooth has a long shaft (1) and a large tridentate head (2) with one small, sharp denticle (3) and two wide, rounded denticles(4). This is the principal magnetite-reinforced, cutting tooth used by T. marmorea to scrape microalgae and associated organisms from the rock surface.
The image and text in Jones & Baxter (1987), is at variance with this description of the rhachidian tooth, which is based on Kaas & Belle (1985) and SEM images in this account.

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