In an ideal Roman cremation, the body was carried in procession from the house of the deceased to a place outside the city, where it was burnt on a pyre until it was reduced to bones and ashes (cineres or favilla). The pyre should be built specifically for the deceased; having to use someone else's pyre was a sign of poverty, or an emergency procedure. The cremated remains might be buried where they had been burnt, usually in a ditch which was filled in and covered or marked; in this case the tomb was called a bustum. More usually, the cremation was carried out somewhere other than the final resting place, at a spot designated ustrina in Latin literature. This might be within the same tomb-precinct or columbarium, as in many tombs at Ostia, or at a separate public site. The bones and ashes therefore had to be collected up and placed in a container, preferably a specially made and ornamented one (cinerarium, oss(u)arium, olla, urna), to be placed in the tomb. The force of the fire, the raking and collapse of the pyre during burning, and eventual quenching with cold liquid would together normally be sufficient to reduce the bones to small fragments which would fit easily into the container. This sort of burial of the remains is assumed in such wishes for the dead as:
I pray that you rest quiet and safe in the urn, bones,
And that the earth is not burdensome to your ashes.