1887 Retained Die Break Or Just A Die Crack?

Looks complete, rim-to-rim. I'd call that a Retained Cud. See if you can see any surface displacement.

I see no displacement of the die face so it is a die crack and not a Retained Cud.

Chancellor, there's also - as Conder mentioned - a " Retained Cud" where the piece is actually no longer connected to the die, but still striking due to the tight fit in the press. It's characterized by notable field displacement; under the right viewing, you can see where the Cud's position on the z-axis doesn't match the rest of the coin yet.

I called it that; Conder called it not. It's been my experience both that "completed" cracks are rarely found still actually connected to the die, but it's also my experience that when Conder and I disagree, he's right.

Having taken a closer look, I note the crack does not seem to fully extend through the bottom arrow. Wear may have caused this look, but I doubt that so we're going to lean Conder's way on this one.

Either way, this die did not strike too many more after the coin pictured here.