[The shell is a polygonal diamond or square shape]

[The shell is a star shape]

[The shell is a triangular or pointed arrowhead shape]

[Resembles scorpion stinger, with a dramatic sharp curve and humped back]

[Shell shaped like a simple flame]

[Long and conical]

[Heart or spade shaped]

Can be applied via the Candied Heart.
(Can be swapped to any same-species trait the item applies.)

[Twisted shell with a bulbous shape that ends in a point]

Can be applied via the Beached ornament.
(Can be swapped to any same-species trait the item applies.)