This is not a narwhal. I'm calling it a narwhal, but it's a narwhal in the same sense that Mickey is a mouse and Bugs is a bunny. I've taken some anatomical liberties, to say the least.
A narwhal is an Arctic whale related to the beluga. The body is torpedo-shaped, not round like a ball. A narwhal is not blue; it is white, mottled with brownish-black markings on the dorsal side. Like other whales, its eyes are on the sides of its head, not toward the front. Its most distinguishing characteristic (usually only present in males) is its long, spiral left canine tooth that can grow to be 10 feet long. Since it is a tooth, it protrudes from the mouth, not from the top of the head.
If you are looking for a realistic craft about narwhals, this is not the tutorial for you. This whimiscal version plays on the narwhal's nickname, "the unicorn of the sea." Affiliate links below.
Whimsical Clay Narwhal
Use the Model Magic to shape the rounded body of the narwhal. Its tail fin should be gently forked. Form two small triangular pectoral fins. Set all three pieces aside to air dry.
Coat a toothpick with craft glue and twist a piece of embroidery floss around it to form the narwhal's tooth. Set it aside to dry completely.
Paint the narwhal's tooth an off-white so that the toothpick and the embroidery floss are the same color. Let the paint dry. As you can see, I didn't paint the one end - that's the end I was holding and that would be hidden once I inserted the tooth.
When everything is dry, assemble the narwhal by gently pushing the toothpick into the narwhal's forehead (again, we're going to "unicorn of the sea," not realism). Glue the eyes in place and give the narwhal a Sharpie smile. Glue the fins to the body.