My first time hearing the word “biodegradable” as a kid was after asking my dad why he threw his cigarette butts into the water when we were fishing.

I tried the first episode but barely got a quarter way through. Made me too sad

In the waters around coral reefs I’ve always noticed a constant clicking/scraping nose. I was told as a kid that’s the sound of the coral polyps but I never really looked into it. Grew up snorkeling a whole lot in my home country and that was the first thing your post made me think of.