No need to fret over the coraline, actually exposing the pores on the LR is a good thing as it will provide additional surface for more beneficial bateria to grow. Not to mention the coralone will grow back.

Looks like you got a good deal... Keep an eye on the brittle star if you have any small fish.... as they grow larger they've been known to prey on them, originally only the green brittles were though to exhibit the 'arch behavior' but recent reports of the brown/black ones doing the same thing on occassion.

BTW you can't always trust the 'number of views' counts, search engines hit the board dozens of times a day and they bump the thread view counts just as a member would, particularly the most recent 100 threads/posts.