News Animals Urchins are dying off across the Caribbean. Scientists now know why A type of single-celled microorganism associated with coral diseases is to blame In the Caribbean, dying sea urchins (one shown at right in 2022) were found to be loaded with a type of microorganism called a scuticociliate, which was absent from healthy urchins (one at left). I. Hewson/Cornell Univ. Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Anna Gibbs April 19, 2023 at 2:00 pm Since early 2022, sea urchins have been mysteriously dying off across the Caribbean.