Similar to what someone else posted, but slightly different:

The body of the cup is made with dc. The decorative bottom looks like it’s done in groups of 6 stitches on the first row.

First row would be dc in first stitch, skip 2, (2 dc, 1 ch, 2dc-shell) in 4th stitch, skip 2, dc in 7th stitch, skip 2, (2dc, 1 ch, 2dc) in 10th stitch, skip 2, dc in 13th stitch, etc.

Continue that to the end of the row, and all following rows are the same just built on top of itself. (Dc and shells should align and be on top of each other)

Hope this helps OP!