This may be a sebaceous cyst. This type of bump develops when sebaceous glands are blocked. Sebum builds up and a bump develops. This bump can feel hard to touch. Sebum is naturally produced, so there usually is not inflammation.
Those two are the muscular system and the excretory system because you use your muscles to push up and down and your excretory system produces the sweat you use while doing them
Spiritual Wellness is <span>Possessing meaning in life and being driven by personal values</span>