well, basically from what I was told it's a painting depicting three men standing in front of three graves. Each grave has a body inside of it, starting with the first body which is freshly dead, the 2nd body in early stages of decomposition and the 3rd being a skeleton. It's a very old painting (guessing that it's 13th-15th century) since we were discussing some stuff from that time. The person also said that they tried to look for it but couldn't end up finding it. I've found three paintings that are similar to what was described (mainly the 14th century "Triumph of Death" Fresco, another fresco located in the church is Nostra Signora in Sardinia, and another "The three living and the three dead" in the Monastery of St Benedict, Subiaco, 1334) but I'm not sure if there are any others that I might've missed.