This conch shell is from Toshikazu Kawasaki again, from the book Origami for the Connoisseur by Kunihiko Kasahara and Toshie Takahama. It is folded from a single piece of square paper, from an A4 sized copier paper (recycled from old printouts of Java articles). It took me about 30 minutes to fold this. It’s not too difficult though it looks a bit daunting at first. Thanks to Pierre for lending me the book! I need to get a copy of it for myself :(
This is the top view.
This is the almost-side view.