To draw a conch shell, you must recognize four features of the shell: its mouth, coils, thickness and overall size. Not paying attention to these features could result in your drawing looking more like a formless swirl, a snail or some other shell. Correctly utilizing these features in your drawing will provide what artists call "verisimilitude," or truth in art. In this case, it means your conch shell will look like a conch shell and not some other type of shell.
Sketch a hand-sized "lemon drop" shape that will serve as the outline for the entire shell. Conch shells are large shells that will barely fit in your hand.
Sketch a mound on top of the shell's outline that extends about three-quarters from the tip to the other side. This mound will represent the shell's mouth. It should also be 20 to 25 percent of the height of the outline.
Outline the inside of the mouth, allowing for a 1/4- to 1/2-inch thick wall.
Create texture on the shell's outline, which can consist of spines or bumps, by shading. Use either straight lines or cross-hatches for shading. Straight line shading consists of straight lines drawn closely together to indicate dark areas or far apart for lighter ones, and cross-hatching consists of lines crossing one another at a slight angle. If cross-hatching, make the "hatches" more numerous and more tightly packed inside crevices and curls; increase the distance between hatches (crossed sections) around the broad curves of the shell to mimic lighter surfaces.
Draw a series of "m"-shaped curves along the upper and lower outside edge of the outline opposite the mouth's opening. These curves indicate the back of the shell's winding coils.
Divide the end of the shell opposite the mouth into concave columns, with the end of each column lining up to each of the rolling "m" curves along the back of the shell's outline.
Erase the sketch marks between the outline, the mouth and the texture.
Color the conch shell with shades of blue or pink. Make the inside of the mouth darker than the outside of the shell and shade the areas around the inside of the coils.