Four completely unrelated questions.

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Sorry about how random these questions sound; I've been wondering about them all for a while.....any input on any of them would be appreciated.
(1) Everyone says that coralline algae is beneficial which is nice to hear coz I have loads of it.
In what way is it beneficial exactly?
(2) What are those reddish..pink, small and angular shapes that grow out of live rock?
(3) When you feed brine shrimp there seem to be lots of tiny bits of organic matter that aren't eaten by the fish.
Can these be eaten by filter feeders such as tube worms or is it pointless adding them to the water?
(4) Do fish have ears?
P.S. I would be really pleased if someone could attempt to answer my plea for help below

 

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Thanks for the replies.
So the major benefit of coralline is that it prevents undesirable forms of algae?
I have a lot of this angular stuff too. It comes in different shapes and sizes. Never thought that it might be coralline.
Interesting response to the ears question. My dictionary mentions "living wholly in water". My lfs had some "fish" with arms that climb out of the water and "play" on polystyrene platforms. Boy were they weird. I'm not an expert on evolution but these have to be some kind of link between sea-life and life on land.