The bug
If you place a budding amethyst, then reduce the world border so that the amethyst is just outside the border, and you activate a piston (that is in the world border) to push at the amethyst, the piston activates, breaking the amethyst, and retracting the piston plays part of the animation.
Can confirm, this works with any block, that the piston can destroy. For example this also works with leaves, pumpkins and melons. There might already be a ticket for, this, but I couldn’t find one.