I agree with wallyB keep the rocks, you can probably get away with a muriatic acid and chlorine dip, then rinse with RODI, and cure for a couple of weeks if you feel the need to.
i never cured the bit of Tonga branch and vanuatu island rock i kept after the fact, and have now been in 3 different display tanks with No issues, and in my current DT. I have a strong feeling something contaminated your water in turn slowly killing off your livestock. By the way Bulk Reef Supply has a video on the acid/chlorine dip for live rock, check it out.
i never cured the bit of Tonga branch and vanuatu island rock i kept after the fact, and have now been in 3 different display tanks with No issues, and in my current DT. I have a strong feeling something contaminated your water in turn slowly killing off your livestock. By the way Bulk Reef Supply has a video on the acid/chlorine dip for live rock, check it out.