Ark of the Covenant – Wikipedia

The Ark of the Covenant (Hebrew: אֲרוֹן הַבְּרִית ʾărōn habbrīṯ; Koinē Greek: Κιβωτός της Διαθήκης, romanized: Kībōtós tis Diathíkis also known as the Ark of the Testimony, or the Ark of God), is the most sacred relic of the Israelites.It consisted of a pure gold-covered wooden chest with an elaborate lid called the Mercy seat.

https://en.wikipedia.org/wiki/Ark_of_the_Covenant