I have a red tree sponge that is at least 3 feet tall now. Growing right out of the top of the tank!
Okay, I'm kidding! But I do have one that has been hanging around in my reef tank for about a year or so. It has survived several tank changes (once to upgrade to the 90 and twice because of a flood). It has never been exposed to air, however. Also have a "breadcrumb sponge" which is the size of a softball or so, and multiple ball sponges that came as hitch hikers on live rock. They were exposed to air for extended times when shipped to me and they continue to thrive in spite of that. Some are in the shade and others are right out in full light. The tank is nutrient rich though, as Skriker mentioned, so maybe that has something to do with keeping them successfully??