An old Masonic symbol that nowadays is mostly part of systems of additional degrees such as the York Rite (“Royal Arch” degree) and the Royal Arch.
The Ark of the covenant is -of course- a symbol of the covenant of the Jews with their God.
Les Plus Secret Mysteres (1820) says of it:
The Ark of the Covenant, which contained the Tablets of the Law, the Rod of Aaron, &c.
Interestingly, the image can also be found on an image (of a tracing board) of the oldest known ‘high degree’ ritual from 1747. See here.
The other ‘ark-like’ image is the table with showbread.
Top: Duncan’s Masonic Ritual and Monitor (1866) by Malcolm C. Duncan
Bottom: Dąbrowski P. 170. Year and designer unknown. Some online sources say that image comes from a document in the Bibliothèque Nationale de France. Their website calls it: “Tableau de la loge de maître”