A round character is a character we know mostly about, so an example of a scenario would be:
There was once a young girl named Sally, she is very tall, with brown eyes and dark black hair. She loves chocolates but hates sushi. But the one thing she loves the most is her sister Chey
Makes sense! If it doesn’t make sense then nobody would understand.
If this is how you've presented the question, Its a bit hard to answer it when one hasn't read these books. It'd be best if you'd put both books into a summary for us to go based off of, at most.
Coralline algae, sponges, and other organisms contribute is a fact. All the others are opinions
hope this helps:))