Question

What is the one thing that is unique to cardiac cells?

Answer 1

One thing that is unique to cardiac cells is the intercalated disks. These are the junctions of two fibers end of one start of another and the cardiac muscles are connected to the intercalated disks. In addition, the three characteristics of cardiac muscles are interdigitating folds, mechanical junctions and electrical junctions gap junctions. 

Answer 2

Cardiac cells unlike all the other cells in the body have a branching morphology another unique feature are the intercalated disks between the muscle fibers which skeletal muscle cells do not have they do both have myofibrils though.