The gravel sea cucumber, Neopentadactyla mixta, burrows in coarse, typically mobile shell sand, gravel or maerl where water flow is quite strong. The gravel sea cucumber is an infaunal burrower and is only visible when the tentacles are projected above the surface.

Neopentadactyla mixta is a sea cucumber of up to 20 cm in length. The cylindrical body is buried in the sand, only its 15 to 30 tentacles emerge. The tentacles are bushy and 10 cm long. They are used to catch and bring plankton into the mouth, in the middle of the tentacles circle.

Neopentadactyla mixta Description: The tentacles of this sea cucumber are found emerging from coarse gravel or maerl. They are white in colour flecked with varying amounts of brown, so that some individuals may appear brown in colour. The body is long and tapering with five rows of tube-feet.