Systems and methods for controlling the temperature of items such as a sample in a vessel or a specimen, in a thermal bath using thermally efficient pellets as the thermal media. The pellets are typically oblong metallic or oblong metallic-coated pellets with rounded edges, a hardened surface, a smooth polished finish, and characteristics that enable efficient thermal communication between the bath's thermal source, the pellets, and the items that are inserted into the mass of pellets. Further, the pellets are dry and moisture and gas impermeable, and they resist microbial growth and are readily decontaminated by several methods including applying an antimicrobial compound to the pellets. The thermal source is controlled to achieve the desired temperature of the items inserted into the pellets.