As gaffer well said they are called
dud tal-blat and are very good bait both for bottom and surface fishing. we used to collect them with a brush. Sometimes we used to put a piece of wet rag with a small piece of stone on it and small pieces of sliced wet bread from a day before we go fishing than the next morning we used to pick it up fast preferably before sunrise and put it in the bucket you have to be very fast or else they will vanish. The rag will be filled with these crawlers. We used to hook 2 on each hook in a way that they stay alive best to hook them from the back. I don't recommend to use on big hooks.

;DHaha memories from my childhood.