system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's the purpose of the cartilaginous tab over the ear hole?

Most people's ears have a cartilaginous tab that fits right over the ear hole (to block it), if you presse with the finger.  Safe to say that's the purpose it serves?
gpt
Update: ok, after learning from a video that the floppy part of the ear is called the "pinna" it made me want to dig around to find what the name of that "tab" is, and turns out it's called the "tragus".  Now armed with a googleable name, the search was on, and it appears that the tragus does aid in collecting sounds from behind (and interestingly in bats it's even more evolved to function even better in that way).

Still, for me it will always be an earhole sealer, when needed:)