Helixir is a free tool for Windows 95/NT that allows you to easily create a variety of 3D helical shapes for use with POV-Ray and Moray
ShellyLib Home Page - Shareware
A small library to create shapes and textures of seashells and snails by Randolf Schultz
ABWTwist: Twisted Shapes for POV-Ray
ABWTwist is a utility to create data files for the POV-Ray ray tracer, Version 2.x and onwards by Andy Wardley. It creates twisted spirals of spheres, cubes or blobs that grow or shrink in size, spiral in or out, rotate, stretch or contract. In particular, ABWTwist is ideal for creating organic looking twisted creatures.