A distinct (including reflections and rotations) arrangement of adjacent squares on a grid, also called a fixed polyomino.
Lattice Animal
See also
Animal, Percolation Theory, PolyominoExplore with Wolfram|Alpha
References
Delest, M.-P. and Viennot, G. "Algebraic Languages and Polyominoes [sic] Enumeration." Theoret. Comput. Sci. 34, 169-206, 1984.Read, R. C. "Contributions to the Cell Growth Problem." Canad. J. Math. 14, 1-20, 1962.Referenced on Wolfram|Alpha
Lattice AnimalCite this as:
Weisstein, Eric W. "Lattice Animal." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LatticeAnimal.html