Brown-lipped Agate Snail (Metachatina kraussi)

Family Achatinidae

This is still a young on, about 3cm in shell length hence the black body.
Extract from Dai Herbet’s “Land snails and slugs of eastern South Africa”

Shell large and heavy, with a thickened outer lip and a columella that is straight but merges smoothly with the base of the outer lip; entire outer surface covered with dense, minutely crinkly axial threads, which form fine granules on the early whorls and below the suture. Ground colour generally off-white, with flames of brown visible on the spire (often extending over the entire shell in dwarf examples); in fresh shells the aperture margins are dark brown to purplish-brown. 

Periostracum thin and brown, flaking off after death and in old individuals. Maximum length about 160 mm, although the species may become adult (or at least thicken its lip) at only 73-90 mm.

A characteristic member of the KwaZulu-Natal coastal biota, commonest in Zululand. Distribution extending north to beyond Maputo in Mozambique, inland to Ithala, the Lebombo Mountains, Kranskop, Glencoe and the Vryheid region, and tapering off in the south to reach Ifafa on the KwaZulu-Natal south coast. It mainly inhabits dune and coastal lowland forest, thick valley bushveld and savanna woodland.

Metachatina kraussi is the largest and heaviest South African snail. Indeed, its shell is thick enough for it to have been used by the Iron Age inhabitants of KwaZulu-Natal in bead manufacture, small pieces of shell being ground into discs, which were then bored and threaded onto string.
The lack of a definite cut-off point to the base of its inner lip is diagnostic of Metachatina, but in juveniles the columella is truncate as in other achatinid genera; they also possess a slight umbilicus and a colour pattern of brown streaks that ends abruptly along a line at the periphery of the last whorl. An adult may produce 20-30 eggs per clutch, each varying in diameter from 8.3-11.8 mm.

The lack of a definite cut-off point to the base of its inner lip is diagnostic of Metachatina, but in juveniles the columella is truncate as in other achatinid genera; they also possess a slight umbilicus and a colour pattern of brown streaks that ends abruptly along a line at the periphery of the last whorl. An adult may produce 20-30 eggs per clutch, each varying in diameter from 8.3-11.8 mm.