Steve Nicholls / Naturalised Spring / Giant Dutch crocus (Crocus angustifolius) flowering, Inkpen Crocus field, SSSI, Berkshire. UK, March

GEORGETTE DOUWMA / Mantle of Crocus giant clam (Tridacna crocea) colours come from symbiotic zooxanthellae in tissue, Misool, Raja Ampat, West Papua, Indonesia.

Georgette Douwma / Crocus giant clam (Tridacna crocea) Rinca, Indonesia

Georgette Douwma / Mantle of Crocus giant clam (Tridacna crocea) Rinca, Indonesia

GEORGETTE DOUWMA / Crocus giant clam {Tridacna crocea} Banda Is, Moluccas, Indonesia

GEORGETTE DOUWMA / Crocus giant clam {Tridacna crocea} Red Sea, Egypt