What happens to ice at zero temperature if it is immersed in water at the same temperature?

Since the temperature of both water and a piece of ice is the same and equal to 0 degrees Celsius, and this same temperature is the temperature of water hardening and ice melting, then the mass will play the decisive factor:

1) if the mass of water is greater than the mass of ice, then a piece of ice immersed in water will melt;

2) if the mass of water is less than a piece of ice immersed in water, then the water will crystallize and turn into ice.