Question

what is dry ice call so

Answer 1

 Dry ice is basically solidified carbon dioxide.Thus it may also be called as carbon dioxide cube.
(ii) Unlike ordinary ice, dry ice does not melt into a liquid but changes directly into CO2 gas, a phenomenon known as sublimation. It changes into gaseous state at and above -78.5 degree Celsius. Thus Solid dry ice exist below temperature of -78.5 degree Celsius

Answer 2

Because it directly changes from solid state to gaseous state... By process of sublimation.