A transparent vacuum formed vessel 1 is filled with a liquid 3 at room temperature that will become a solid at freezing temperature and a low density float material 4. After freezing, the vessel is turned upside down so that upon thawing, the vivid colored float will move to the top of the vessel showing a thaw. The devise can be reused.The same concept can be used as a cooking aid by using a transparent sealed tubular 1 assembly inserted in the food with a solid cylinder 3 that will melt at some critical temperature allowing the low density float to rise to the top of the indicator visibly protruding from the food. More than one meltable cylinder, 3 & 8 and float, 4 & 5 may be used as a warning and ready indicator.Combinations of solid dense particulates and low density materials may also be used for color changing indicators. A permanent magnet attached to a float can be used to trigger an audible alarm, which can be incorporated in various cooking utensils to show cooking temperatures and times.