"Using the included play hammer and chisel, kids can crack open each reusable play geode and discover the translucent plastic gemstones inside. Gems double as manipulatives, and come in eight different colors and four different shapes - you might find a red heart, a purple triangle, a green diamond, or more fun combinations. In addition to helping kids learn early sorting, matching, and counting skills, Rock 'n' Gem Surprise also introduces kids to early STEM and geology concepts without the messy clean-up associated with real rocks and geodes. Each of the set's two-piece play geodes pops apart and snaps back together for endless learning fun - crack 'em open again and again!"-- Manufacturer.