Purple sea urchins are eating all the kelp in California. But in Pittsburgh, hundreds of miles from the ocean, we order them in the mail.

They arrive wrapped in wet newspaper with pieces of seaweed to snack on. We keep them in tanks, next to some sea star buddies, and study how they grow skeletons. When we're done, we bleach them (the university considers them a biohazard) and save them as extremely fragile decorations.