As shown in Monstrous Biographies: Cap'n Buck, it was built at Monstro City's Port, made by Captain Buck's crew. The ship has become infamous due to the rarity of Buck's visits. In Moshi Monsters, it docks at The Port and functions as a shop. It rarely visits as it contains treasures brought back from Buck's adventures that are all backed up with storyline featured on The Daily Growl. This means the goods are always different each time he visits. You have a one-time opportunity to get the items.