Contact with the nematocysts or stinging cells of certain species of the flower-like marine coelenterates causing severe dermatitis with chronic ulceration. In some cases, signs and symptoms of a systemic reaction develop, including headache, nausea, vomiting, sneezing, chills, fever, paralysis, delirium, seizures, anaphylaxis, cardiac arrhythmias, heart failure, pulmonary edema, and collapse. In rare cases, it is fatal.