Slipper limpets can be bought shelled ready to use and frozen, these make a good bait but they are too fresh; a better bait is got by collecting your own after a storm has washed them up on a beach. Birds are quick to find them, shells on the promenade at Weymouth and crows on the beach were the sign that the bait in the photograph was there for collecting, thanks to a storm three or four days earlier.
Do not rush to freeze the bait, the slipper limpet works best when it is 'a bit ripe'. The meat of the limpet is quite easy to remove from the shell, a fairly blunt knife like the one in the photograph is used to twist under the shell to lever it from the one it is clinging to and then the tip is run around the edge of the orange 'foot' where it attaches to the shell; when this is loose the knife can be used to gently pull the dark body portion from under the white shell dividing section.
Slipper limpets are a very good bait to use for species that patrol the beach looking for such a bait, bass, flounders, sole and plaice are very keen on them, on their own or in a cocktail with lug or ragworm.If you are fishing from a pier, harbour wall or jetty you will find that most fish will readily take this bait.
The limpet flesh is soft and will not take hard casting, but then.... if you will realise the fish are coming in close to find just the bait you are offering, it would defeat the object of using it if you cast it a long distance. You can bind the bait on with bait elastic to stop it flying off or tiny fish pulling it from the hook.