The reason why you need to stir the kettle deeply after putting the malt in. The steam rising distorts the picture a little but without grain in the kettle, this view shows the malt settled at the bottom. The darkness inside the ring is the malt at the bottom.
If you don't stir deeply and thoroughly, the malt can just sit at the bottom. The beer you'd end up with is not what you wanted.
Thanks to Dave @Deja Brew for pointing this out.
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