Great! and sorry for the mix up, vicious spisces is kind of a name you wouldnt think a girl would have..no offense or anything, i'll assume you know what i mean.
I saw a posting once of a cave that used lava rock. The guy made the whole back of his tank into numerous caves using lava rock. I wish I could find the link because he had detailed pictures and everything. The finished product looked amazing.
He bought brown plastic eavetrough and cut to to length for his tank. He attached enough sections together to fill the tank from top to bottom. He then cut holes big enough for his fish and put a few dividers inside the gutters so that he could have many separate caves. Once that was complete he took black silicone and glued the lava rock to the outside of the gutters until he had a complete wall of rock. He then attached it to the back of his tank.
I always though that it would be a great way to hide the heater and filter in/outtakes.