The 6-polyiamond illustrated above.
Crown Polyiamond
See also
Crown Graph, PolyiamondExplore with Wolfram|Alpha
References
Golomb, S. W. Polyominoes: Puzzles, Patterns, Problems, and Packings, 2nd ed. Princeton, NJ: Princeton University Press, p. 92, 1994.Cite this as:
Weisstein, Eric W. "Crown Polyiamond." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CrownPolyiamond.html