1. Hair – Hair extends into the dermal layer within hair follicles. Humans have about five million follicles. They protect our bodies against cold and UV radiation and produce sebum.
2. Palmar Skin – The unique patterns on the palms, known as palmar skin, are similar to fingerprints and can be used for identification. These tiny wrinkles and folds help improve grip and enhance tactile sensitivity.
3. Cat Skin AND 4. Frog Skin – Your skin is the largest and heaviest organ. It weighs around six pounds and is about 2 millimeters thick. It is thinner on eyelids and thicker on the soles of your feet. Each inch of skin contains nearly 19 million cells.

Sources:
– Cleveland Clinic. (2022, April 25). Integumentary System: What It Is, Function & Organs. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22827-integumentary-system
– Hoover, E., Alhajj, M., & Flores, J. L. (2023, July 30). Physiology, Hair. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK499948/
– Olympus LS. (2020). Palmar Skin. Olympus-Lifescience.com. https://www.olympus-lifescience.com/en/microscope-resource/primer/anatomy/brightfieldgallery/palmarskin10xlarge/#:~:text=Similar%20to%20fingerprints%2C%20the%20patterns,and%20to%20enhance%20tactile%20sensitivity.