I love all the goodies you get with live rock! I have gotten Brittle stars, a sifter star, bristle worms, copopods and a few I can't identify as they are always a bit out of sight. IMO, it just ads to the tank making it more natural reef. The last photo you think is aptasia (The black thing?), I don't know as I don't believe aptasia is black. Does it look like this;

aiptasia13.jpg

This is Aptasia...

Good luck...