Abrasion of car tires is recognized as a major source of microplastics in the environment. The composition of these particles is highly complex, including rubber, a diverse array of chemical additives and heavy metals. Various of these compounds can leach from the particles into the marine environment presenting a cocktail of chemicals to marine biota. Still, little is known about the effects of car tire leachates on marine species. The aim of this study was to test the effects of car tire leachates on the early development of the three dominant species of sea urchins in Gran Canaria: Paracentrotus lividus, Arbacia lixula, and Diadema africanum. We prepared leachates of micronized car tires (