Seals were small, engraved devices used to make an impression, usually on clay or wax. Seals came in various shapes, including cones, squares, cylinders, and even animal heads. Seal impressions could indicate ownership or authenticate a document, and they could be used to secure bags or openings, such as doors or entrances to tombs.

 Seals were fashioned out of a variety of materials, including bone, limestone, metal, semiprecious stone, or wood. Sometimes the names of the owner and his father were inscribed on the seal. Some seals showed the owner’s title.

 In order to authenticate a document, the owner of the seal would press its engraving into the clay, wax, or other soft substance affixed to the document. (Job 38:14) The substance would then harden and hopefully prevent someone from tampering with the document.

 Seals could be given to another person, thus giving him the owner’s authority. An example involves a Pharaoh of ancient Egypt and the Hebrew man Joseph, son of the patriarch Jacob. Joseph had been a slave in Egypt. Later, he was unjustly imprisoned. In time, though, Pharaoh released him and elevated him to the position of prime minister. The Bible says: “Then Pharaoh removed his signet ring from his own hand and put it on Joseph’s hand.” (Genesis 41:42) Because the signet ring had an official seal, Joseph now had the authority to carry out his important work.

 Queen Jezebel of ancient Israel used her husband’s seal in her plot to murder a man named Naboth. In King Ahab’s name, she wrote letters to certain elders, asking them to accuse innocent Naboth of cursing God. She placed the king’s seal upon the letters and succeeded in her evil scheme.—1 Kings 21:5-14.

 The Persian King Ahasuerus used a signet ring to authenticate his official orders.—Esther 3:10, 12.

 The Bible writer Nehemiah states that Israelite princes, Levites, and priests showed their approval of a written covenant by applying their seals to it.—Nehemiah 1:1; 9:38.

 The Bible mentions two occasions when seals were used to secure entrances. When the prophet Daniel was thrown into the lions’ pit, “a stone was brought and placed over the entrance of the pit.” Then, King Darius, ruler of Media and Persia, “sealed it with his signet ring and with the signet ring of his nobles, so that nothing could be changed with regard to Daniel.”—Daniel 6:17.

 When the body of Jesus Christ was placed in a tomb, his enemies “made the grave secure by sealing the stone” that was rolled in place to block the entrance. (Matthew 27:66) If that was an official sealing by imperial authority, then “the seal would be clay or wax pressed into the crack between the . . . stone and the tomb’s entrance,” says a Bible commentary on Matthew by David L. Turner.

 Because ancient seals can shed light on the past, archaeologists and historians take a lot of interest in them. In fact, the study of seals, called sigillography, has become a major field of study.