One of my incubated chick eggs started to move yesterday on day 20, and than today day 21 it has stopped movin?

My egg started to move and wiggle yesterday on day 20, and than today on day 21, the egg was moving in the morning, and now for about the past 8 hrs it has not moved at all. Does this mean the chick has died? How do I tell without opening the egg? This is my first time incubating chicken eggs. Thanks