Koi Fish
$20
Estimated value as of 2026 · Multiple sources including Kodama Koi Farm, Chewy, and Aquarium Whisperer[1][3][9]
Koi fish are colorful ornamental carp commonly kept in backyard ponds by hobbyists.
Fun fact The highest recorded sale price for a single koi fish was $1.8 million in 2018[3].
koi-fishornamental-fishpond-fishlive-animalsaquarium
More in Nature
$31.8M
Fossil Tyrannosaurus Rex Skeleton (Stan)
Nearly complete T-Rex skeleton auctioned for research and display.
$27 million
Californium-252 (per gram)
Rare synthetic element produced in nuclear reactors, the rarest element in practical use.
$5M
Moon Rock Sample (From Apollo 17 Mission)
Lunar basalt specimen collected during humanity's final Apollo mission in 1972.
$350M
Hope Diamond
A 45.52-carat deep blue diamond with a legendary curse.