That galaxia looks to me like hammer coral. This is a pic of galaxia, and it wouldn't be good to have in a 20long unless it's the only coral in there. It's very aggressive and has very long sweeper tenticles. Hammer coral are fine, they can be aggressive, but not as bad as galaxia !
Galaxia
I believe the "blue xenia" you have might be anthelia. Here's a pic of some that I have in my 50
Very nice looking tank BTW ! Nice and clean !
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