congruent prime

A congruent prime contains "shapes" of identical digits nested about the center when drawn in the form of symmetrical figures and polygons. The original prime can be constructed by concatenating each row left-to-right, top-to-bottom, as oriented in the drawing. E.g., 111181111 is a square-congruent prime.

1 1 1
1 8 1 
1 1 1