Good or Bad stuff in my tank??

[bryanh11]

My aquarium has been up and running well for 2 years. I have some soft corals, and live rock with 5 fish. and my hermits and snails. and a cleaner shrimp.
over the past year there are some strange things spreading on some of my rock. on is a black "tar" looking stuff. One is a Lavender, or light purple thick stuff. they seem to slowly keep spreading and they are now about 2 or 3 inches in circumfrence (if thats the right word).
also at night these worms come out, some are very long. they are pink and look like centipedes.
please let me know if all this is fine, or if i need to get these things out....
the black stuff
this picture came out turned 90 degrees wrong, but its the lavender stuff below the leather soft coral. or in the picture its to the left of the leather coral...looks like a brain.
one of the live rock "pink" worms...

 

[saxman]

The black stuff is either a sponge or a tunicate...if it reacts to touch it's a tunicate, if not, it's a sponge. That being said, I'm pretty sure it's what is commonly called a "chicken liver" sponge.
The pink work is a bristle worm...they're a good part of your CUC, and feed on carrion, detritus, and leftover food. I've even seen them eat red cyano. Some peeps love them, some hate them...however, we're of the "love them" camp.