English: The production rule is (a ↦ ab) (b ↦ c) (c ↦ aad) (d ↦ e) (e ↦ a) with initiator e, iterated for 27 generations. l(w_n) = A193147(n−7) + ... + A193147(n−3). The incidence matrix has reducible characteristic polynomial f(x) = x⁵ − x⁴ − 2x² − 1 and dominant eigenvalue ρ² ≈ 1.75488 (the plastic ratio-squared). The central tile and its five subtiles have areas in the ratios ρ¹⁰ + ρ⁵ : ρ⁸ : ρ⁶ : ρ⁴ : ρ² : 1. The viewport height is 2.3 and the origin is at the centre of the spiral. Empirically, the fractal boundary has box-counting dimension 1.11. Conjecturally, with dim_box(fb) ≈ ½log_ρ(λ), λ is the real solution of λ³ = λ² + 3.