Alex Mustard / Hearth heart urchin (Maretia planulata) which usually lives buried in the sand, crawls along the seabed. Dauin, Dumaguete, Negros, Philippines. Bohol Sea, tropical west Pacific Ocean.
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Constantinos Petrinos / Longspine heart urchin (Maretia planulata) burrowing into the sand, Lembeh Strait, North Sulawesi, Indonesia.
