One of the four 5-polyiamonds are called pentiamonds.
Pentiamond
See also
Pentiamond Tiling, PolyiamondExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Pentiamond." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Pentiamond.html