Step 1: Start by drawing the shell for which we draw a sideways triangular head with a curved bottom. Now draw a curved loop from behind the head.
Step 2: Draw spiky curved patterns across the entire shell.
Step 3: Draw a large circular eye between the head and the shell and shade it in.
Step 4: Draw tentacles by drawing random loops connected with each other. Make sure to make their ends rounded.
How to Draw a Cartoon Nautilus – Step-by-Step Tutorial