Neither tacks nor men, Tackmen appear to be pitch-black one-eyed heads supported by thin tendril-like spikes, when in actual truth they are amorphous blobs peering in through a crack in space and time. Seemingly apathetic, Tackmen will sarcastically roll their eyes whenever given attention. Secretly they adore fellow Tackmen, as such the bigger ones often “grow” above the smaller ones to protect them.
They are incapable of standard movement, but can "slide" back into the crack where they came from - and appear elsewhere. As such they are capable of trans-dimensional travel, and if a Tackmen's trust can be earned, that particular Tackmen will be happy to relay messages for you. Merely looking at a Tackmen's eye is enough to seemingly understand and transmit messages.