Squeezing acne and squeezing out the hard black stuff is a mixture of sebum plugs, sebum, dander and mites. 1. Sebaceous plugs: The surface layer of sebum that clogs pores can appear black after direct contact with dust or oxidation. 2. Dandruff: Due to the constant shedding of the epidermis, black pimples can appear after mixing with dust. 3. Mites: When a mite infection exists, the body of the mite can be squeezed out along with the acne. Therefore, mites may also be involved in the composition of the hard black substance. Lastly, it is recommended to seek medical attention when black hardness is squeezed out of acne.