In Shelled Gastropods
The peristome is the margin of the aperture of a gastropod shell. It is the edge of the lip of the shell. This part is sometimes reflected (turned back) or thickened once the snail reaches adult size, and these qualities of the peristome can be diagnostic features of the shell which may aid in identification of the species.
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Famous quotes containing the word shelled:
“We are born each morning, shelled upon
A sheet of light that paves
The palaces of sight, and brings again
The river shining through the field of graves.”
—Philip Larkin (1922–1986)