This detail image shows color and spines of the rapacious sea star Crown Of Thorn (Acanthaster planci), maybe the most dangerous enemy of stone corals. If Crown of Thorns occurs in large populations they are able to destroy large coral reefs completely. Doesn’t it looks like an invulnerable fortress?
Hurghada, Egypt, Red Sea
Canon EOS 50-E with 2.8/100mm Macro in Subal Housing, Subtronic amphibian flash, TTL, 1/60, f16