Here is an ice cube which is stuck at the bottom of a drinking glass. Normally, ice floats on water because solid-state H2O is less dense than liquid-state H2O.
Here is a sunken ice cube due to embedded glass marble ball. Dihydrogen monoxide (H2O) in solid state is about 9 % less dense than H2O in liquid state. Therefore, an ice cube floats to the top of a drinking glass. However, if a heavy foreign object is embedded during ice formation, resulting ice cube sinks to the bottom.
