Puget Sound at low tide is a joy well known to many in the region. It’s a formative experience for many children here, overturning rocks to see all the tiny crabs and sea stars that live amidst colorful seaweed, kelp and barnacles. But few people are as versed in the lesser-known critters that live in the tidal zone as Seattle naturalist Kelly Brenner . She specializes in anything without a backbone. Brenner is the co-founder of an online event called #Invertefest , which challenges anyone who