Sharkbone

The Sharkbone is an enemy that appears in Mario & Luigi: Superstar Saga and its 3DS remake, Mario & Luigi: Superstar Saga + Bowser's Minions, where it is found in Gwarhar Lagoon. The name of the enemy was originally based on unused enemy name text, and it also appeared as the undead shark's name in the Nintendo Power guide. The easy mode hints in Mario & Luigi: Superstar Saga + Bowser's Minions officially refers to them as "Sharkbones".

Sharkbones are skeletal shark-like creatures that always appear in groups with the dorsal fin-wearing Sand Cheeps; both remain submerged up to their dorsal fin in the sands in order to disguise themselves. Both enemies are also often fought with Beanerang Bros.

Battle
In battle, Sharkbones and Sand Cheeps appear under the name ????; only their dorsal fins are visible, making it hard to tell them apart. In Mario & Luigi: Superstar Saga + Bowser's Minions, the top of any Sand Cheeps present will be visible for a few seconds at the start of the battle, which in turns hints at the position of any Sharkbones. They attack by swimming through the sand to stop in front of one of the Mario Bros., then surface for a moment before lunging and trying to bite their target. The attack can be dodged or countered by jumping, and poisons Mario or Luigi if they are hit. The Bros. must watch the enemies carefully to avoid jumping prematurely and hitting a leaping Sand Cheep instead. Any Sharkbones and Sand Cheeps that have attacked and were not defeated will promptly shuffle positions after their turn, making it harder to track them.

If the brothers perform a Thunder Bros. attack or an Advanced Fire Bros. attack on a group of Sand Cheeps and Sharkbones, any Sharkbones that are hit will immediately attack the Mario Bros., one at a time. In addition, targeting one of the underground enemies with the Advanced Thunder Bros. and Chopper Bros. attacks will reveal their identity as Luigi uppercuts them out of the ground.

In Mario & Luigi: Superstar Saga + Bowser's Minions, Sharkbones are level 25, which makes them distinguishable from the level 24 Sand Cheeps. The easy mode hints will also show which of the enemies named "????" are Sharkbones.