Generally, these are referred to as individual "luncheon" plates in the marketplace.  However they are part of Wedgwood's extensive "Wreathed Shell" dessert service.  Here they are offered in Wedgwood's whiteware body with a very pale pink glaze -- slightly more intense at the edges.  They are part of an extensive catalog of dessert pieces including a large footed shell centerpiece (with stand), sauce tureens and serving dishes, all based on actual shell shapes.  In addition to the plates, we have occasionally seen individual sauce dishes, butter pats and even an oyster shell shape.

One caution here -- beware, these may be considered the gateway drug to much more extensive collecting. 

Wedgwood called their shell dessert ware designs into service with a number of treatments over a long period of time and under different names.  An eighteenth century creamware version with enameled border is referred to as the "Nautilus" service. According to Robin Reilly the pieces offered here are part of the "Wreathed Shell" service, based on the "Argonaut" shape fruit center.  We have seen these pieces offered in an ivory body with transfer decoration, a green majolica type glaze, "Moonlight Lustre"and other lustre decoration, as well as contemporary white blanks.  The design dates from the late eighteenth century, through the nineteenth,  with sporadic revivals in the twentieth, ranging from an "Alpine Pink" (C. 1937), to a green majolica like glaze in the 1960's, and to a bone china with pearl lustre glaze in the1980's. (Robin Reilly, Wedgwood, The New Illustrated Dictionary, pp. 118, 292)