how draw shell in python

1import turtle as t
2import math
3n = 1
4size = 25
5t.speed(0)
6for x in range(16):
7    t.fd(size*n)
8    t.lt(90)
9    t.fd(size)
10    n = math.sqrt((n**2)+1)
11    t.lt(180 - math.degrees(math.acos(1/n)))
12    t.fd(size*n)
13    t.lt(180)