There are various obstacles in Pet Rescue Saga that make it more difficult to clear a level. As you get farther in the game, you will encounter many more obstacles of increasing difficulty. See below for examples of obstacles and how to clear them.
Caged blocks prevent you from popping the block in the cage. The cages can be removed by popping blocks next to them or by purchasing the Mesh Mash Booster from the store. This turns the caged blocks into normal blocks.
Planks and other Immovable Objects
Planks or other immovable objects prevent you from dropping boxes straight down. Instead, the blocks on top of these obstacles will fall to the left or right, but only after you have removed any blocks touching them. When you need to clear a percentage of blocks or rescue pets, you will need to keep in mind how blocks and animals will behave once they drop on a plank or similar object.
Bombs in Glass Cases
In some levels you will encounter bombs and bombs in glass cases. Uncased bombs can be exploded simply by clicking on them. However, enclosed bombs will need to touch a plank or reach the bottom to turn into normal bombs. Although a normal bomb is usually helpful by clearing a small area of blocks, a cased bomb can become an obstacle if it is located near the top of a stage and preventing blocks from combining.
Locked Stone Boxes
These locked boxes can only be unlocked with keys. The keys will be available in any level containing stone boxes. Extra keys can also be purchased in the store, however, these are never necessary to beat a level. Once a key is used on this obstacle, the stone box becomes unlocked and disappears.