Photo of a floor mosaic at Sephoris, Israel showing a triclinium.
The guests leaned next to each other while eating sitting on the floor or some sort of mats/cushions.
Some have wondered if Jesus' "Last Supper" may have been eaten while seated at a triclinium. The Gospels indicated he and disciples ate in a furnished upper room. After supper Jesus got up from the table. It was not stated that this was a triclinium, only a table was described.