This is a commonly used word, for the processed ashes and grinded bone fragments. It is combined out of two words: Cre-mation and Re-mains.
A Retort is the machine in which a cremation takes place. They are also commonly known as Crematory, which technically is the facility, and not just the machine.
Cremation is the process of reducing body remains to basic chemical compounds in the form of gases and bone fragments. This is accomplished through high temperatures and vaporization. Contrary to popular belief, the cremated remains are not ashes in the usual sense, but rather dried bone fragments that have been pulverized in a device called an electric cremated remains processor. This leaves the bone in a fine sand like texture and color, able to be scattered without any foreign matter.
If your pet was cremated along with his/her favored play toy, blanket or collar that was brought along with your pet, the ashes may vary in color, due to that some of the materials was probably fire-retardent/fire proved.