Just make it!
Do you ever think of anything cool to make when you're bored? Well...I do, I <3 turning trash to something cool or useful! So I'm going to share one of my favourite project to you!:) ENJOY!
For the second step, check if it's the shape you want and if it's not, you can always cut the edges to change the shape. Now, when you're comfortable with the shape,use an empty soda can to polish the sharp edges from the shell. (edges of shells are always sharp)
<< From the round part of the soda can.
For the last step, use a sharp object to make a hole on your beautifully shaped shell(be careful, if your sharp object is too thick, the shell might crack, so use something like this.
After making a hole on your shell, get a jump ring(make sure it fits the hole!) and get through it.
When the jump ring is through the hole, remember to close it! You can ethier use your teeth or pliers to close it.(Well... I used my teeth) When it's done, don't forget to take an old necklace from your jewelry box and wear it! ENJOY<3