ground? WTF, holes in the leaves, fairly large and half the stem gone to hell. 95 percent chance of croaking. Only a wee little seedling. Could it have been a cricket or something?
if it was really chewed up only a couple of things come immediately to mind.
grasshopper/ locust
or
moth caterpillar
neither seem very likely, but both are possible, and they would do that amount of damage in a matter of minutes.