The coral, called palythoa, can typically be purchased anywhere saltwater fish are sold. Despite their small size, the toxin they release can be deadly.
http://www.wwltv.com/article/news/local/texas-mom-warning-others-after-aquarium-coral-nearly-kills-her-family
http://www.wwltv.com/article/news/local/texas-mom-warning-others-after-aquarium-coral-nearly-kills-her-family