Hippo Iron

The Hippo Iron (ヒポアイアン Hipo Aian) is a creature developed by Dr. Indigo for Shiki's plot to use monstrous creatures to attack East Blue to force the World Government to submit to him.

Keeping it's twin tusks hidden, this crafty hippo-beast pretends to be harmless. Hiding the huge fangs inside its mouth it deceives its prey.