Knit Nature Motif: Scallop Shell

Note The shell is worked from the top.

Using larger-size needles and A, cast on 5 sts by knitted cast-on method .
1st row (RS) K.
2nd row P.
3rd row Cast on 3 sts, p3, k5.
8 sts.
4th row Cast on 3 sts, k3, p5, k3. 11 sts.
5th row Cast on 5 sts, [k5, p3] twice. 16 sts.
6th row Cast on 5 sts, p5, [k3, p5] twice. 21 sts.
7th row Cast on 3 sts, [p3, k5] 3 times. 24 sts.
8th row Cast on 3 sts, k3, [p5, k3] 3 times. 27 sts.
9th row Cast on 3 sts, k3, [p3, k5] 3 times, p3. 30 sts.
10th row Cast on 3 sts, p3, [k3, p5] 3 times, k3, p3. 33 sts.
11th row K3, p3, ssk, k1, k2tog, p3, k5, p3, ssk, k1, k2tog, p3, k3. 29 sts.
12th row [P3, k3] twice, p5, [k3, p3] twice.
13th row [K3, p3] twice, ssk, k1, k2tog, [p3, k3] twice. 27 sts.
14th row P3, [k3, p3] 4 times.
15th row Change to B, k3, [p3, k3] 4 times.
16th row As 14th row.
17th row K3, p3tog, [k3, p3tog] 3 times, k3.
19 sts.
18th row Change to A, p3, [k1, p3] 4 times.
19th row K3, [p1, k3] 4 times.
20th row Change to B, work as 18th row.
21st row S2kpo, [p1, s2kpo] 4 times. 9 sts.
22nd row P1, [k1, p1] 4 times.
23rd row K1, [p1, k1] 4 times.
24th row As 22nd row.
25th row S2kpo, p1, k1, p1, k2tog, slip st just made on to left-hand needle, pass next st over it, slip it back on to right-hand needle. 5 sts.
26th row P1, [k1, p1] twice.
27th row K1, s2kpo, k1. 3 sts.
28th row P.
29th row S2kpo. Fasten off remaining one st.

Using A and smaller-size needles, RS facing and starting at 28th, pick up and k7 sts along B row-ends of right-hand edge.
1st, 3rd, and 5th rows (WS) K.
2nd row Ssk, k3, k2tog. 5 sts.
4th row Ssk, k1, k2tog. 3 sts.
6th row Sk2po. Fasten off remaining one st.
Work left-hand edge to match.

Using smaller-size needles and A, with RS facing and working into each cast-on st, pick up and k36 sts around top edge, taking 1 st from each st plus 1 extra st from cast-on of each 5-st rib.
Next row Using-larger size needles, k4, kfb, [k8, kfb] 3 times, k4. 40 sts. Bind off knitwise.
Press to shape.

Directions reproduced with permission from 75 Birds, Butterflies & Little Beasts to Knit and Crochet, St. Martin's Press, 2011

s2kpo slip two stitches as if to knit two together, knit one, pass the slipped stitches over
sk2po slip one knitwise, knit two together, pass slipped stitch over

k= knit k2tog = knit two together
Kfb = knit in front and back of st p = purl
p3tog = purl 3 together RS = right side
ssk = slip, slip, knit st(s) = stitch(es)
WS = wrong side