Answer:
The pinna
Explanation
The pinna's main job is to gather sounds and funnel them to the eardrum
The common example of sublimation is shrinking of ice cubes that are not used in the freezer and conversion of dry ice rapidly into wispy clouds which vanish very soon
Natural barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid. Also, the normal flow of urine washes out microorganisms that enter the urinary tract. The immune system uses white blood cells and antibodies to identify and eliminate organisms that get through the body's natural barriers.
Answer:
About 450 million years ago
