6. Two differently sized cubic building blocks are glued together, forming the three-dimensional shape shown in the right figure. Among them, the four vertices of the small block's glued face are the one-third points on each side of the large block's glued face. If the edge length of the large block is 3, then the surface area of this three-dimensional shape is $\qquad$


Analysis: As shown in the figure, the area of each of the four triangles is $1 \times 2 \div 2=1$,
so the area of one face of the small block is $3^{2}-1 \times 4=5$.
The surface area of this solid figure is the surface area of the large block plus the area of four faces of the small block. Therefore, the area is $6 \times 3^{2}+4 \times 5=74$.