Those are impact craters. The question is what is the composition of Hyperion. What it is composed of will define what the impact craters look like.
Solid rock would not give that type of impact picture. Perhaps a rock and ice mixture could give this picture. If Hyperion were solid rock, we would see rays from the impact craters, as on the moon, that are caused by ejecta from the impact. It would appear that Hyperion is a semisolid.
My first guess would be that its largely made of fine dust like flour with low enough gravity that the craters don’t collapse.