This applet allows students to create images of shells using a mathematical model of shell form. The model used in this demonstration is very simple, and yet has proved very powerful. The model is also of historical importance. It was first demonstrated on computer at a time when most people thought computers were rocket science - literally. The pioneering work of David Raup introduced the use of computers to the science of paleontology in the early 1960s.
Higher values mean opening of the shell becomes wider with each rotation.
D affects the distance of the center of the tube from the axis of coiling. Higher values mean tube of the shell forms further from the coiling axis. T affects the distance of the center of the tube from the previous rotation along the axis of rotation. Higher values mean the shell is taller. Once you've made your selections from the sliders, click the Draw button or click the image of the shell to redraw the image.