Pentomino5x4

Press the Green Flag to activate pentominoes display of a 5x4 rectangle on a three second delay between tilings. 

The input is from the very exhaustive and beautiful pentomino tilings at   isomerdesign.com

In this instance the 5x4 - https://isomerdesign.com/Pentomino/5x4/solutions.txt

All of the pentominoes except the "X" are able to be in a 5x4 tiling. I think that is is interesting.