So I picked up a large chalice and due to the flow in the cube, it can't go in the front of the tank. So the only spot big enough and lower flow is where I have this huge mushroom. If you took a tape measure from one end to the other, I would guess it's about 10"-12". Due to it laying on the sides of the rock, it does not take up that much room but it's still about 6-8". I have no place for it in my 60g as it's just too big.
I would like this gone ASAP as I had to put it in my sump. I think $25 is a fair price. I would also entertain trades.
Sorry, for some reason I never got the email that someone replied to this thread until today when I logged in and saw I had a new "like" so clicked it. I would have probably donated it to the school too. This one did sell about 2 weeks ago and I did have another one about 6" that I just sold today when someone came to pick up some chaeto. What all are you looking for in your school tank? I'm not sure how far I am from you, but if you feel like making the drive I could find a few things to donate to the kids.