"The previous oldest one was from France and is some millions of years younger," Adiel Klompmaker, a University of Florida researcher, said of the 100 million-year-old crabs. "So this discovery in Spain in quite impressive and pushes back the origin of spider crabs as known from fossils."
"It just doesn't happen every day," Klompmaker said of finding two new species of spider crab within two hours at the dig sight in 2008.
Klompmaker added that the many of the crustaceans found at the reef probably died off after an environmental event destroyed their habitat.
You can read more about the discovery at Live Science.