Many teachers and students have experienced the classic pet rock experiment in conjunction with a geology unit. A teacher has students bring in a "pet" rock found outside of school, and the students run geologic tests on the rock. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster. While this type of lesson is concise and direct, the authors have found a new way of targeting the same Earth science benchmarks for upper elementary students. Their inquiry-based approach allows students to discover geologic properties as they befriend their pet rocks. (Contains 2 figures and 3 online resources.)