Histology is the branch of science dealing with the study of tissue.
When investigating corals, small tissue samples are removed and then placed in a fixative to preserve the tissue. These samples are then decalcified to remove coral skeleton. Once the skeleton is removed the tissue is processed and sliced into thin sections that can be viewed under a microscope.
Analyzing tissue samples from diseased corals enables systematic characterization of diseased tissue and helps to guide further disease investigation.