Monster Donut

Monster Donut was a chain of donut shops across the United States.

Description
The shops are connected with the life force of the Hydra, as another Monster Donut shop popped up somewhere every time the Hydra grew two heads (after losing one). It also seemed to be magic as the shops grew out of thin air. Tyson thought that their donuts were exceptionally good. Most chain stores and restaurants, like Monster Donut, are connected to the life force of a Hydra (or any other type of monsters). This was stated by Annabeth as being the reason some stores pop up so fast. This trick was discovered by some children of Hermes in the late 1950s.

The Sea of Monsters
After Percy, Annabeth, and Tyson escape the Princess Andromeda, they hide in an old hideout created in the days when Annabeth, Thalia, and Luke were on the run. Wanting some privacy with Annabeth, Percy tells Tyson to go out and grab some donuts. They are surprised when he comes back with a box of donuts, so they go explore the area and see that there is a Monster Donut shop nearby. Apparently only monsters are able to purchase the donuts (which is the reason why Tyson is able to do so) while demigods are killed and it appears partly because Tyson wished it. The Hydra eventually connects to Monster Donut then appears and attacks the trio. They are saved by Clarisse, who uses a cannon from the Confederate Ironclad battleship, CSS Birmingham, to slay the Hydra.

The Mark of Athena
Monster Dounut sponsors a section of the Georgia Aquarium owned by Keto and Phorcys. While Percy Jackson, Gleeson Hedge, and Frank Zhang are being given a tour by Keto, Percy saw a red sign which he had to read twice because of his dyslexia which said this section was sponsored by them, reminding Percy of the first time he had to fight the hydra.