what is the slime that snail's trail made of?

Answer 1

Mucus is a very complex substance containing complex molecules called mucopolysaccharides. At times it can also contain calcite crystals and I assume other things we don't know about. In fact the nature of the mucus changes on different parts of a snail's body, sticky and viscous on upper parts and thin and more fluid on the sole of the foot.

Answer 2

mucus.