If they die they wont poison your water .Those 2 corals if they are indeed the ones i sayd are verry beautifull,fast growers corals just arent for beginers.They need high light and constant alk and calcium,little phosphates and pristine water conditions.If they are hard stony corals with a verry thin layer of flesh that hass small polyps they are the corals i sayd but if they are soft then i was wrong .