Reishi fruitbodies develop relatively slowly and less predictably than oyster mushrooms, which I think makes them really interesting to watch. These photographs show slightly more than a month of development.

The  fruitbody starts out as a shapeless blob, then gradually grows into a recognizable shelf or bracket form. This one started emerging from the opening in its bag on August 3 of this year, and grew rapidly in the summer heat and humidity. It has since slowed a bit, but keeps growing 36 days later. 

Day 1

Reishi primodium day one 

 Day 4

Reishi day four 

Day 6

Reishi day six 

 Day 19

 Reishi day nineteen

Day 36, front view. Notice the change in strength and distribution of color.  The growing edge is white, while the central area has gotten dark brown (the lighting in all these photos is somewhat reddish due to the effect of the tent housing the mushrooms, so the color isn't really true to nature). The dark area has also lost its sheen; that results in part from the accumulation of brown spores on the surface. Even though the spores come from the pores under the shelf, they accumulate on top!

 Reishi day 36

Day 36, view from above. You can see the shelf shape, color, and spores more clearly in this view.

 Reishi day 36, top view

Here's a question to ponder: why do you suppose the shelf grew so thick, from top to bottom? Can you see a way the grower  might influence the ultimate shape it takes?