Heathcliff wrote:
It's an 18-inch
diameter blob (roughly spherical) of concrete with a shallow (maybe 6
inch) hole in the top. This thing is way too heavy to put out with the
trash. So, how do I break it up for disposal?

Around here, our trash collectors won't take any concrete.
Call the city garage. That's what I did when I had to dispose of
concrete from an old sidewalk. They didn't charge me a dime either.
I just used a sledge-hammer to break it up. Not sure how well that'd
work in your situation, though.

-Felder