coil, whorl, roll, curl, curlicue, ringlet, gyre, scroll

a round shape formed by a series of concentric circles

• corolla — (botany) the whorl of petals of a flower that collectively form an inner floral envelope or layer of the perianth
• calyx — (boany) the whorl of sepals of a flower collectively forming the outer floral envelope or layer of the perianth enclosing and supporting the developing bud; usually green
• verticil — a whorl of leaves growing around a stem

• round shape — a shape that is curved and without sharp angles