the mucus can cause a reaction on human skin. My boffin advised wearing rubber gloves when on 'safari'. He also advised dropping them into a jar of bleach solution. This also kills and is less smelly than salt water.
When they are ready to reproduce, they develop a lump. The skin splits and one of the black eggs slips through the slit. It looks like a shiny black bead. The egg contains up to 10 tiny flatworms which can survive immediately. They grow on until they split the egg and then go off on the hunt.