Hanne & Jens Eriksen / Comb sea star (Astropecten polyacanthus) in shallow water, Oman, August

Hanne & Jens Eriksen / Comb sea star (Astropecten polyacanthus) digging itself into the sand, Oman, August

Nick Upton / Spiny comb starfish / Sand star (Astropecten irregularis), inspecting Common mussels (Mytilus edulis) after being washed into a rockpool during a storm, St.Bees, Cumbria, UK, July.

Jeff Rotman / Armored / Spined seastar (Astropecten armatus) on seabed at night, Galapagos Islands, Pacific Ocean.

GEORGETTE DOUWMA / Comb sea star (Astropecten polyacanthus) showing regrowth on two arms. Papua New Guinea

GEORGETTE DOUWMA / Whitespotted puffer / Toby fish (Arothron hispidus) feeding on a Comb starfish (Astropecten polyacanthus) Bali, Indonesia

GEORGETTE DOUWMA / Whitespotted puffer / Toby fish (Arothron hispidus) feeding on a Comb starfish (Astropecten polyacanthus). Bali, Indonesia

GEORGETTE DOUWMA / Comb sea star (Astropecten polyacanthus) Bali, Indonesia.

Ingo Arndt / Common Brittlestar (Ophiothrix fragilis) detail, outstretched approximately eighteen centimeters, North Sea, Helgoland, Germany

Ingo Arndt / Common Brittlestar (Ophiothrix fragilis) detail, outstretched approximately eighteen centimeters, North Sea, Helgoland, Germany

Ingo Arndt / Common Brittlestar (Ophiothrix fragilis) outstretched approximately eighteen centimeters, North Sea, Helgoland, Germany

Ingo Arndt / Starfish (Astropecten irregularis) diameter approximately five centimeters, North Sea, Helgoland, Germany