Bacteria, It's the Only Culture Some People Have! T-Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat This funny science tee is the perfect Christmas, Hanukkah, birthday, graduation, Mother's Day, Father's Day, or retirement gift for someone who loves geeky science puns and dad jokes. Works for a microbiology major, biology teacher, biologist, microbiologist, or germaphobe. Lightweight, Classic fit, Double-needle sleeve and bottom hem