Ashley Cooper / Am Basteir on the Cuillin Ridge, Isle of Skye, Scotland, UK, March 2006.

Doug Perrine / Blue shark (Prionace glauca) tooth from upper jaw, right side, on display at Oceanographic Museum of Monaco, Principality of Monaco (digitally modified)

Chris & Monique Fallows / Mako Shark (Isurus oxyrinchus) at surface with mouth open, Cape Point, South Africa, March.

Chris & Monique Fallows / Mako Shark (Isurus oxyrinchus), Cape Point, South Africa, April.

Pete Oxford / Grey Nurse Shark (Carcharias taurus), Umkomaas, Kwazulu Natal, South Africa

Albert Lleal / Blue Shark (Prionace glauca) lower jaw showing teeth

Fred Bavendam / Titan Triggerfish (Balistoides viridescens) with spines from a sea urchin it has eaten, Bali, Indonesia

Fred Bavendam / Leopard Grouper (Plectropomus leopardus) showing teeth, Great Barrier Reef, Australia

Norbert Wu / Grey Nurse Shark (Carcharias taurus) close-up of teeth and nose, Steinhart Aquarium, San Francisco, California

Norbert Wu / Grey Nurse Shark (Carcharias taurus) close-up of teeth and nose, Steinhart Aquarium, San Francisco, California

Norbert Wu / Fangtooth (Anoplogaster cornuta) cleared and stained to show bones (Red) and cartilage (Blue) deep sea

Fred Bavendam / Grey Nurse Shark (Carcharias taurus) underwater portrait, New South Wales Australia

Staffan Widstrand / Blue-green hydnellum (Hydnellum caeruleum) fungus growing on forest floor, Iggejaur-Varjisan-Labtjevare, Norrbotten, Sapmi, Lapland, Sweden. August.