From the Super Mario Wiki
Shrooba Divers are enemies that appear in Mario & Luigi: Partners in Time, where they are found in the Gritzy Desert. They are green Shroobs with white spots that wear scuba masks and oxygen tanks, and have the ability to "swim" in sand. Their name is a pun on "Shroob" and "scuba diver". Shrooba Divers try to ambush Mario and Luigi by surfacing under them in the overworld. They are fought alone or in pairs, and also appear alongside Pokeys and Bob-ombs.
Shrooba Divers raise their hand and spin as they tunnel under the sand, leaping out to try and dive into Mario or Luigi; Baby Mario and Baby Luigi must counter this attack with the hammer. The Shrooba Diver raises its right hand for Mario, and its left for Luigi. Shrooba Divers can also swim through the sand towards one of the Bros. and circle back towards the other from behind; the attack can be dodged and countered by jumping, and can trip Mario or Luigi if it hits them.
Occasionally, the Shrooba Divers may jump and dive into the sand, then pull out an object to throw at the Bros.; objects thrown with the right hand target Mario, while objects thrown with the left target Luigi. They can pull out either a green Spiny Egg-like or cactus-like ball, or a Sand Cheep. The spiked ball must be dodged by jumping, while the Sand Cheep bounces overhead and will damage the Bros. if they jump into it. Shrooba Divers take critical damage from the Ice Flower Bros. Item, and may drop a Super Mushroom or Blue Pepper upon defeat.
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