Polyomino glider predecessor?

[Axaj]

What's the smallest polyomino glider predecessor?

[knightlife]

This heptomino may be the smallest:

Code: Select all

x = 5, y = 3, rule = B3/S23
4bo$2b3o$3o!

This one is also seven cells:

Code: Select all

x = 4, y = 3, rule = B3/S23
4o$bobo$bo!

The second one has a smaller bounding box.

[Citation needed]

There is a third one. If I remember correctly, there are only three such heptominoes.

Code: Select all

x = 5, y = 5, rule = B3/S23
5o$obo!