Should I be worried about this bubble coral?

[benny_the_clown]

We've had this bubble coral about 2 weeks now and it's bottom skeleton has been exposed the whole time. It's bubbles are fully opened during the day and tentacles come out at night, but it's bottom skeleton has never been fully covered.

Also spotted a small growth on side of skeleton right at edge of flesh (circled below) that kind of looks like a small polyp with small tentacles. This is the best pic I could get. Still a novice and any help appreciated!

Tank is about a year old and good parameters all around, just did 30% water change last week.

 

[Bribo12]

Looks happy to me. The flesh usually doesn’t go all the way down the skeleton. If the flesh starts receding further up then I’d worry. The thing circled is a pineapple sponge, harmless filter feeder and won’t do any damage to the coral.

 

[benny_the_clown]

Looks happy to me. The flesh usually doesn’t go all the way down the skeleton. If the flesh starts receding further up then I’d worry. The thing circled is a pineapple sponge, harmless filter feeder and won’t do any damage to the coral.

Thank you so much! That's a relief.