- The
periostra**** (/ˌpɛriˈɒstrəkəm/ PERR-ee-OS-trə-kəm) is a thin,
organic coating (or "skin") that is the
outermost layer of the s**** of many s****ed...
- the land
snail shown above) also have an
outer s****
layer called the
periostra**** which is
composed of the
protein conchiolin. Some land
snails (especially...
- are
features of the s****,
including crease and an
encrusting layer (
periostra****) that
covers most of the s****.
Gills and
reproductive structures also...
- the
outermost layer,
which in
almost all
cases is all
conchiolin (see
periostra****).
Molluscs never use
phosphate to
construct their hard parts, with the...
-
resembles the quahog, but the s**** of the
ocean quahog is rounder, the
periostra**** is
usually black, and on the
interior of the s****, the
pallial line...
-
family of bivalves: it is
rounder than the hard clam,
usually has a
black periostra****, and
there is no
pallial sinus in the
interior of the s****. The hard...
-
consists of iron sulphides, the
middle layer is
equivalent to the
organic periostra**** found in
other gastropods, and the
innermost layer is made of aragonite...
-
symmetrical s**** with the apex at the middle. It is
covered by a thin
yellow periostra****. Its
closest relative, the
tuatua (Paphies subtriangulata), has an asymmetrical...
- layers, an
outer periostra**** made of
organic compounds and two
biomineralized layers.
Articulate brachiopods have an
outermost periostra**** made of proteins...
- it can show irregular,
concentric zigzags on a
cream background. The
periostra**** is dark
brown and
forms a
broad band
around the s**** margin; it is velvety...
