why was 'the seal' an important urban artefact?

 Seals are important as it gives us useful information about civilization of Indus valley.It is made up of soapstone,terracota and copper.The seal shows us the culture of valley like about there ornaments,skills of artists,religious belief etc.Some of the important seals of Indus valley are The Pashupati seal,the bull seal,The unicorn seal etc.