It is a live-action gift shop on an unidentified beach. The shop contains miscellaneous items, a glass bowl, but mostly knick-knacks (dried sea life).
It is a fairly small wooden shack. There is a clam-shaped sign on the front of the shack that reads the shop's name in red text.
The interior is dark. There is a fishbowl inside on one of the tables and there are lots of dead sea creatures on the inside. There is a table under a lamp to dry the sea creatures, killing them, and there is a bathroom as well.
In The SpongeBob SquarePants Movie, Plankton steals King Neptune's crown and has it sent to Shell City, intending to frame Mr. Krabs for the theft so that he could steal the Krabby Patty secret formula. The alleged city was feared by all in Bikini Bottom, including Neptune himself, as nobody who ventured there ever came back. SpongeBob and Patrick volunteer to go there to retrieve the crown and clear Mr. Krabs' name.
After a hazardous journey, they are eventually taken by the Cyclops to a strange shack on land, later finding out it is Shell City. The shack is filled with hundreds of sea creatures who had been killed and turned into cheap novelties to be put up for sale.
SpongeBob and Patrick almost die when the Cyclops places them on a table beneath a heat lamp, leaving them to dehydrate. However, in their final moments, the lamp short circuits and sets off the sprinklers, reviving the duo and all of the sea creatures imprisoned within. They all proceed to attack the Cyclops while SpongeBob and Patrick escape with Neptune's crown, presumably ending the danger posed by Shell City to those in the sea.