underwater surprise: radiant sea urchin raises from sandy bottom revealing that it is not walking by itself but carried by a crab using the urchin as a shield against predators

urchin diadematidae scuba seabed dorippidae crab critter underwater bottom radiata spike abyss astropyga claw predator dive muck spine protect dorippe indopacific reveal bizarre walk surprise hold yshaped red protection sumo funny sand appear clever shield carry frascone venom radiant kidnapping