Ingo Arndt / Hermit Crab (Anapagurus laevis) in a snail shell from a Common Northern Whelk (Buccinum undatum) approximate length is nine centimeters, Helgoland, Germany

Ingo Arndt / European Flounder (Platichthys flesus) eyes, fish is approximately nine centimeters, Helgoland, Germany

Ingo Arndt / European Flounder (Platichthys flesus) approximately nine centimeters, Helgoland, Germany

Michael Durham / Human (Homo sapiens) detail of a nine year old boy's eye

Norbert Wu / Lamprey (Petromyzon marinus) in parasite phase feeds on fish by rasping through their skin, Salmon River at Lake Champlain, New York