Snail trap door

[Fanof49ASU]

I found this when my turbo died. It appears to have an image of a snail shell....it this typical?
http://markfoltz.freeservers.com/TrapDoor.jpg

[DMBillies]

yup... the mexican turbos have a door like that on their foot. I assume they slowly add to it (as they do their shells) so that it continuously adds to the diameter and the door fits snugly.