There are few feasible models for marine-focused inquiry laboratory activities, a notable shortcoming for instructors seeking to engage their students in meaningful, course-based research experiences (CUREs). We describe a multi-week CURE that investigates the symbiosis between hermit crabs and the hydrozoan Hydractinia spp. Although much is known about hermit crab biology, ecology, and behavior, little is known about Hydractinia, and less is known about the relationship between the two symbionts. Given their small size, low cost, and relative ease of maintenance, colonized hermit crabs may be useful subjects for student-driven research projects. We discuss our experiences with this system and offer adopters a suite of resources for in-lab implementation.