Common Door Snail Balea biplicata
The Common Door Snail remained undiscovered in our garden for a long time. It is a very beautiful creature whose shell resemble shells that can be found by the ocean. The rascal is small though. The entire shell hardly reaches two centimeters en the animal itself is about 0.7 centimeters. It obviously belongs to the family of Door Snails and is also called the Thames Door Snail.
In many cases the correct species can be determined by looking at the opening of the shell, combined woth other features, such as colour, the number and size of the windings etc. But be careful when judging the mouth of the shell: it is an important characteristic, but in adult snails only. Juvenile snails are still building their house. The lip or mouth is not turned yet , very thin and always whitish or in the colour of the inside of the shell. So only adult White-lipped Garden Snails for instance have a white lip. Juvenile Black-lipped Garden snails have a white lip as well! Look at the two bottom pictures of the Common Door Snail. The adult is in the lowest but one picture: the lip has the typical shape of this species, is thick and turned. In the lowest picture an almost fully grown juvenile: there is no lip, the shape is not the typical shape of the species. All because the animal is still constructing its shell. So the typical lips of the adults as shown in guides and on the internet doesn't help you at all when looking at a juvenile. And telling juveniles apart from adults is very difficult too. Size and the number of windings however may help you there. Anyway, this is the reason why it is difficult and sometimes impossible telling apart juvenile snails!
The Common Door Snail is also known under its former scientific name: Balea biplicata.