This block is generated by an error. It can not be connected with any other block, and doesn't have any function. Some Scratchers call it a Hat Block but it is actually a combination of both a hat and Cap Block. It does not have an input, and is the only red block in Scratch 3.0. Unlike other blocks, it does not have an outline. It cannot be commented on, and trying to comment on this block will cause the block to follow the mouse. Going to a different sprite while it's following the mouse will cause the block to disappear, and attempting to go back to the original sprite causes the block to become immobile. Going to the Costumes or Sound Tab and returning to the code will crash the project.