The crates you are looking for come in all shapes and sizes and will either grant you a bonus or damage your health.
Blank Crate
This crate is just blank with no picture on it, it is one of the most common crates in the game. You will always get one piece of wumpa fruit when you break them.
Aku Aku Crate
When one of these crates is broken Aku Aku will appear at Crash Bandicoots side and he will gain a Hit Point.
1-Up Crate
This crate has a picture of Crash Bandicoot on it and when broken a 1-Up will be added to your arsenal.
! Crate
The exclamation crate will trigger all the clear silhouette crates you see.
Breakable Arrow Crate
These crates act as trampolines for Crash Bandicoot and are used to reach higher places.
? Mark Crate
These are unlabeled crates that usually contain big amounts of wumpa fruit. Occassionally they will contain a 1-Up or a Aku Aku mask.
Stripey Crate
These boxs are like the blank boxes but have stripes on them. You use these so you can bounce on them and get 10 pieces of wumpa fruit.
TNT Crates
Although these crates hurt Crash Bandicoot they come in useful for destroying multiple boxes while on the run.
Checkpoint Crate
The check point crates have a C on them and when you jump on them you receive a checkpoint.