Smithsonian 4 Pack Micro Science Kits provides endless hours of science fun. Smithsonian Rock and Gem Dig - Excavate Gemstones and Minerals, Identify Gemstones and Minerals, Learn How Rocks and Minerals Are Formed. Smithsonian Micro Volcano - Build and erupt a volcano. New dual-mold system lets you make the most realistic and accurate volcano ever. Smithsonian Magic Rocks - Instant Crystal Growing Kit, Create a Brilliant Underwater Garden, Rocks Grow to Different Heights up to 4" (10 cm). Smithsonian T. Rex Fossil - Learn About Dinosaurs and Paleontology, over 10" (25.4 cm) long Includes 4 Micro Science Kits: Volcano, Rock n Gem, Magic Rocks and Fossil T. Rex.