Since we are not asking “What else floats in water?”
Use of ancient lead in modern physics experiments ignites debate
Unfortunately the story really doesn’t lay out the case for why ancient lead ballast falls into the category of “cultural heritage artifact” or why more than a small fraction of it would need to be preserved for study. Newly mined lead is contaminated with Pb-210, which has a half-life of about 22 years and is present because it’s in the decay chain of U-238. So Pb that’s been around for several hundred years (especially under water where it would better shielded against any kind of activation reaction) has been separated from the source of the unstable isotope that produces it (ultimately U-238, but realistically Ra-226, which is the “most recent” previous step along the decay chain with a half-life longer than a year) is more useful for shielding detectors, as it has essentially no sources of radiation that might cause spurious readings.
The history of archaeology over the past few centuries is full of elements/artefacts/environment which have been destroyed because even archaeologists at the time could not see how they could be useful. Decades later, new techniques could have extracted more information from these missing artefacts. That’s why archaeologists became incredibly conservative.
One cannot tell which fraction of the lead ballast might be useful without forecasting the next centuries of archaeological techniques and historical interest.
Where would we be in a future wherein what we do not presently know about the past was not ever known? Future museums would empty, masters degrees would not be written, journals would be bereft of speculative debate concerning smaller and smaller looks into less and less important things. Honor the Yukawa potential of history!