How to do it:
Make a ring of 5 ch. closing round with 1 s.t stung on 1° ch.
1° r: 3 ch. 11 d.c. inside the ring
2° r: *3 ch., 3 d.c closed together stung on next d.c from previous r. 3 ch., 1 s.t. stung on same place where you closure 3 d.c closed together (see graphic) 1 s.t. stung on next d.c.* Rep from * to * 5 times. Close the r. with 1 s.t. stung on 3° ch counting from the bottom.
-ch: chain stitch
-s.t: Slip Stitch
-d.c: Double Crochet