A cave, from the water slowly cracking and chipping away at the rock it seeps down into, creating freshwater, but also, slowly creating a cave.
Heart rate, color, irritability, muscle tone, and breathing
Gamma rays because microwaves, visible light and radio waves wouldn’t come in handy if an astronomer would want to study the composition of planets and stars.
Action potentials (i.e. nerve impulses) occur in several types of animal cells<span>, called </span>excitable cells<span>, which include </span>neurons<span>, </span>muscle cells<span>, </span>endocrine<span> cells, and in some </span>plant cells<span>. </span><span>It takes around 40 action potentials for a smell sensation to be reported.</span>
