Mr. Block has pale skin and dark black curly hair. His eyes are light blue and accented with puffy lower eyelids. He wears a black tunic that has a straight collar with red tabs, red cuffs and red piping at the shoulders.
He also has a silver braid over his left shoulder that ends at his upper left chest with a yellow oval devise which has a red knob. It has not been revealed if this devise is a badge of office or a piece of equipment.
Mr. Block conducts himself as though he hates everything. He is rude and condescending to everyone he has been observed interacting with thus far.
In Missing Milo, he is taken hostage by pistachions after Cavendish and Dakota succeeded in saving King Pistachion's seedling. His memory of that timeline is erased when the plant is destroyed in Milo's time before becoming sentient, leading him to think that Cavendish and Dakota's story is an absurd attempt to get off of pistachio-protecting duty.
In Perchance to Sleepwalk, he continues to disbelieve Dakota and Cavendish's claims of saving the future from sentient pistachio trees. After giving them a mission to protect wild pistachio plants from red-beaked crows, he gives them a "receipt". It's a photograph of himself sticking his tong out with the caption "you stink". After he hears the two are destroying the plants themselves, he takes them off pistachio duty and reassigns them to cleaning houses during the Renaissance. He then assigns Brick and Savannah to take their place, much to their frustration.
The image gallery for "Mr. Block" may be viewed here.
Mr. Block is one of only seven characters in season 1 who's eyes are shown with pupils.