P72 quasi-shuttle is a period-72 oscillator (a twin bees shuttle variant) with found by Jason Summers on August 19, 2005. It consists of two B-heptominoes being hassled by two figure eights and two unices. In 18 generations the B-heptominoes are flipped into a centuries and a pair of blocks by unices, which then reacts with the blocks and figure eights to be flipped back into B-heptominoes in 61 generations, but with extra blocks. The extra blocks move the B-heptominoes forward without leaving extra centuries. Although this looks at first sight like a shuttle, it isn't really, because each side of the oscillator uses a different hassling reaction. Like a regular twin bees shuttle, it can reflect gliders.
- 84P72.1 at Heinrich Koenig's Game of Life Object Catalogs