Constituting the emblema of the flooring in a triclinium, this mosaic, with its naturalistic depiction of a skull and the tools of a mason, expresses allegorically the transience of life and the impending nature of death. It is the libella, the level, from which hangs the plumb-line -the instrument that serves to control the levelling of a construction- that symbolises all equality: from its ends hang in perfect equilibrium the symbols of power (the sceptre and the royal purple) and on the right, the sack and the stick, symbols of poverty. The skull -with a line of darker tesserae outlining the sutures of the cranium- and the level -an instrument that we known only through depictions from the Roman period, shown here with clearly illustrated bronze elements and its wooden structure- underline the intent to depict them with precision.