They are encountered twice in the game, in the Gateway Hall on Bryyo and in Botanica in Eastern SkyTown, Elysia. As the name implies, they are blocks that must be pulled with the Grapple Lasso to make platforms for Samus to use.
The Blocks in both appearances look very different. On Bryyo, the blocks resemble a Mogenar-class War Golem's head, and feature two red eyes. When pulled, a second block falls out from behind it, creating a platform. This is done so that Samus can get back up onto the ice bridge.
In Botanica, there are two blocks that must be pulled to ascend the room. Scanning them reveals that they once stored nutrients for the Cyrlic trees in the chamber. Additionally, they are adorned with the Chozo Artifact symbol.
In Metroid: Samus Returns, they appear as blocks with red Grapple Points that Samus can pull using the Grapple Beam (expelled from her Arm Cannon). Some Pull Blocks are destructible while others can only be moved. They tend to be obstacles that must be moved or destroyed to open up paths and/or shortcuts. They are called Pull Blocks in Metroid: Samus Returns Official Guide. They differ from blue Grapple Points which are indestructible and immovable Grapple Points.
The Zeta Metroids and Queen Metroid both have parts of their bodies that can be grappled like Pull Blocks: the back and tongue, respectively. When Samus first encounters the Diggernaut, she mistakes its eye for a Pull Block and accidentally activates the robot in the process.
Metroid Prime 3: Corruption scans
- Gateway Hall
- "Statue does not appear to be attached to the ground and could be pulled with enough force."
- "Container can be pulled out from wall. Once used to store nutrients for nearby flora."
- Inhabitants & Eco System of SR388 (p. 27)
- "Pull Blocks are not hidden, and they function differently from most other blocks. Some Pull Blocks can be destroyed, while others can only be moved. No matter which type of Pull Block you encounter, the solution for dealing with them is always to pull them with the Grapple Beam."