Earth Glide. The elemental can burrow through nonmagical, unworked earth and stone. While doing so, the elemental doesn't disturb the material it moves through.
Elemental Nature. The elemental doesn't require air, food, drink, or sleep.
Siege Monster. The elemental deals double damage to objects and structures.
Multiattack. The elemental makes two slam attacks.
Slam. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.
Grasp of the Grave (1/day). The elemental can summon a mass of worm-eaten, bony arms from the ground beneath one target within 60' of the elemental. The target must succeed on a DC 16 Strength check or be grappled.
At the start of the target's next turn, it must make another DC 16 Strength check. If it succeeds, it breaks the grapple and the bony arms sink back underground. If the target fails, then it is restrained as it is dragged up to its waist into the ground.
At the start of the target's next following turn, it must make another DC 16 Strength check. If it succeeds, the bony arms sink back underground and the target remains buried upto its waist in the ground. It can then use an action to make a strength check to unearth itself on the same turn, ending the restrained condition. If it fails, the target is dragged 6' underground. It can then use its actions on its turns to make strength checks to be able to use its movement to burrow to the surface at a speed of 5' per round.
If at any point the elemental takes damage while using this trait, it must pass a concentration check or the feature ends prematurely.