flushed stones different than surgically removed stones?

I ended up having to have surgery to remove an enormous stone that was lodged in my gallbladder duct (along with the gallbladder, of course). I wish I had started flushing sooner!! They said that there was no bile in the gallbladder, though, I think the stone was blocking any from getting in..

Anyway, prior to the surgery, I did a flush, and got out about 115 small soft rubbery round or unusually-shaped angular green blobs. And after the surgery, they gave me the stones that they removed. They're nothing alike.. The stones removed surgically are mostly cube-shaped, and very hard like beads. They're more like the consistency of bone, and they're colored a deep goldish brown
The giant stone - 2.5 cm, almost perfectly spherical is mostly gray, with rust-colored patch on it, but hard as a rock.

Could it be that the flushed ones are the "younger" ones? And perhaps the only ones that could squeeze past the giant one? Interestingly, an ultrasound was taken prior to my first flush, with I'm trying to get hold of... But the second ultrasound, after first flush, but prior to surgery, showed a bunch of small stones at the back of the gallbladder, an empty space in the middle (perhaps where the flushed stones came from?) and then the giant stone blocking the duct..

Any opinions on why the stones looked so different?
thanks!
LaurenK