These ships are made of pre nuclear era steel and it's used for special instruments that measure radiation and other uses where even traces of nuclear
fallout would affect the reading. en.wikipedia.org...
The fact that the shipwrecks were the last resting place for hundreds of Allied servicemen who died fighting the Japanese, and indeed some of their
remains were very likely still in the vessels when they were grubbed up, meant nothing to the animals that committed these crimes. They were war
graves.