An article published in the journal “Science Advances” reports the discovery of a marine arthropod dating back to about 95 million years ago, during the Mid-Cretaceous period. A team of researchers led by paleontologist Javier Luque of the American Yale University announced the discovery in Colombia and in the USA of hundreds of exceptionally preserved specimens of various species that include the one so far unknown that they named Callichimaera perplexa. It’s a crab that represents the oldest swimming arthropod known after the extinction of sea scorpions, which occurred about 250 million years ago. Its strange features could lead to rethinking the definition of crab.