Growing your own 'live rock'?

I work around a lot of marinas in south jersey, and noticed some even have sponges growing in there basins. I was wondering if I were to grow some 'live rock' in one of these basins, giving it's a cooler environment than my tropical reef tank, say in the low 70's during the summer months compared to the upper 70's of our reef tanks. Would it 'acclimate' to my warmer tank temps, including the little hitch hikers that may tag along? It doesn't take long around these parts to get a nice covering of growth on things.

Seasons just starting for us around here with the warmer temps setting in now, so I think I'll set a basket of rock just below the surface where it will get plenty of light and see what grows on it in a few months.....what kind of hitch hikers ect. Just wondering if any one else has had any chances to experiment with localy grown rocks?

Thanks, and I'll keep you informed of my experiments,

Dave