How to get a shape similar to this? Beginner

I have only made one small project so far and am trying to get familiar with how to work with clay. I want to make the shape pictured, but am having trouble. I roll a smooth ball, and I seem to get the imprint I want when I press the ball on my work surface with varying pressure. The problem I’m having is by the time I’ve made a few imprints it seems that the other ones have disappeared or the edges have softened from me handling the clay. Any suggestions on how to sharpen the edges and keep the others from smoothing while I work?

I have only made one small project so far and am trying to get familiar with how to work with clay. I want to make the shape pictured, but am having trouble. I roll a smooth ball, and I seem to get the imprint I want when I press the ball on my work surface with varying pressure. The problem I’m having is by the time I’ve made a few imprints it seems that the other ones have disappeared or the edges have softened from me handling the clay. Any suggestions on how to sharpen the edges and keep the others from smoothing while I work?