From the Super Mario Wiki
Bob-omb Blocks are a type of block that appear in Mario vs. Donkey Kong. They are blue blocks with a red light in the center. The only way for Mario to destroy these blocks is to have a Bob-omb explode next to them. Bob-omb Blocks are usually placed in ways where they are obstructive to Mario's progress, but can sometimes be used as bridges in certain levels. They give 100 points when blown up.