Got a kick out of this add

[Snaz]

Long ago before when reef tanks, LR and trickle filtration were new to North America, dead corals were a must for a marine tank, or so we were told. Without the dead coral the pH would drop etc etc. Every year the hobbyist would swap out his dead corals, bleach them with chlorine and sunshine and put them back in his tank pristine white and biological filtration was handled but undergravel filters.

He is probably right in that you cannot buy coral skeletons easily anymore.