As dark and scary as the deep blue sea itself, a black coin like the Deep-sea Anglerfish has never been seen before. When illuminated with ultraviolet light its secret is revealed as you come face to face with a scary sea monster. A highlight of Luminous Marine Life, the fourth coin in the 3 euro series is more than worthy of a sea creature that could not be more extraordinary.

With a spherical body, large head and a mouth packed with sharp teeth, deep-sea anglerfish are bizarre-looking creatures found below a depth of 300 metres in all the world's oceans. With a body length of between 6 centimetres and 1.2 metres, it is amazing how much larger the female is than the male, which tends to reach only a few centimetres in length.

To catch their prey, female deep-sea anglerfish are equipped with a ‘fishing rod’ (illicium) and attached ‘lure’ (esca), which is usually equipped with a luminescent organ. The internal structure of the esca is complex and includes a bewildering variety of vesicles filled with luminescent bacteria. In addition to the esca’s luminescent organ, all species of the genus Linophryne possess a light-producing barbel on the hyoid bone. However, the barbel’s light does not come from light-producing bacteria but from a photogenic granulate lying between the cells. The independent development of two different light-producing mechanisms in this genus is unique in the natural world.