SEB is characterized by diffuse areas of tissue loss exposing skeleton that is eroded and covered by the external casings of the ciliates (vacated loricae of Halofolliculina) that have a salt and pepper appearance. Living tissue is typically separated from algal colonized skeleton by a non-uniform (1 – 10 cm thick), black to dark-green, undulating, annular border.
At low densities, ciliates may appear as sparsely scattered, dark dots on skeleton recently denuded of tissue, producing a characteristic speckled appearance. At high densities, ciliates form a thick dark band that grades into areas of sparsely scattered, vacated loricae.
The locations of lesions associated with SEB vary among coral species and also as lesions progress across colonies. Most infections originate basally, progressing to the branch tips in branching colonies, while they are often located centrally in hemispherical, sub-massive or encrusting colonies. SEB can also appear at the margin of any previously denuded lesion, and they are often associated with white syndromes, especially during the later stages of an infection.
Without magnification, dense bands of Halofolliculina ciliates can appear similar to black band disease. However, SEB infections tend to be more speckled in appearance. In contrast, BBD lesions are characterized by discrete black bands composed primarily of cyanobacterial filaments that overly live tissue and can be readily dislodged. BBD lesions also lack the eroded calices often seen in SEB infections.
SEB has been recorded on 82 species of scleractinian corals, in 26 genera and 12 families, as well as the hydrozoan coral, Millepora. The family Pocilloporidae and Acroporidae are the most susceptible scleractinian families to SEB.