From Longman Dictionary of Contemporary Englishsnailsnail /sneɪl/ ●○○ noun [countable] 1 
HBAa small soft creature that moves very slowly and has a hard shell on its back2 → at a snail’s pace
HBAa small soft creature that moves very slowly and has a hard shell on its back2 → at a snail’s paceExamples from the Corpus
snail• Making a shell is costly for a snail.• If insects, worms and snails could scream, would you still light that bonfire?• At different points along a trail the child sees snails-different snails each time.• Some of these, such as most small snails and limpets, are quite harmless.• Unfortunately, the snail spread across the island and caused widespread destruction to crops.• The snails had vanished, but now some one seemingly had traced a picture of a butterfly in the dirt.Origin snail Old English snægl 