The stone seals of Harappan civilization are covered by

Most of the seals were made of steatite, which is a kind of soft stone. A few of them were also made of terracotta, gold, agate, chert, ivory and faience. The standard Harappan seal was square in shape with a 2X2 dimension. It is believed that the seals were used for commercial purposes

Explanation:

the correct answer is the following is a list of inventions made in the medieval islamic world, especially during the "islamic golden age" (8th to 13th centuries),[1][2] as well as the late medieval period, especially in the emirate of granada and the ottoman empire.

science and technology in the islamic world adopted and preserved knowledge and technologies from contemporary and earlier civilizations, including persia, india, china, and greece-roman antiquity, while making a number of improvements and innovations.