Crown of Thorns starfish (Acanthastrea plancki).  Uncommon in Chagos, this species has reached plague proportions in many parts of the world where, because it feeds on corals, it causes considerable damage to coral reefs.  Curiously, it was most common around the Three Brothers in both 1978 and 1996, but has not been seen in plague numbers.  However, in 1978, huge areas of bleached corals were seen in Speakers Bank, with many of these starfish around the edges of the dead area, in 1979, so occasional outbreaks here may occur.
