Not very descriptive?

Describe plastic bait holder?

Carp anglers use plastic looking bags (PVA Bags) that melt when they come into contact with water, you can also get PVA string/tape to bind bait or whatever on, again once in contact with water it will start to melt away, takes a few seconds easily long enough for bait to be cast and hit the bottom, only downside is if the bait itself is wet (watery) then it will melt the PVA before you get a chance to cast.