This reliquary takes the architectural form of a two-story altar, with a shell niche in the upper story framing enameled figures of the Crucifixion. In the lower story, a rock-crystal cylinder displays a cross that was believed to incorporate a fragment of the true cross, and the capsule below contains a supposed relic of the sponge held to Christ's mouth when he was on the cross. The upper mount of the cylinder is engraved "LIGNVM.CRVCIS.SPONGIA.SAL[UTA]RIS" (The wood of the cross; the alleviating sponge).