In contrast to most other echinoderm tube feet, those from sea urchins exhibit especially high aspect ratios due to their need to extend past their protective spines for stability, mobility, and feeding purposes. In adult sea urchins, the extended tube foot aspect ratio can be as high as 50:1, while in juveniles, this ratio is closer to 10:1. The tube feet are in turn connected to the urchin's water vascular system, with each tube foot acting semi-autonomously as a hydrostat-like actuator. In our UrchinBot prototype, an analogous bellow-type actuator was designed and fabricated mirroring that of a juvenile (post-metaorphic) urchin. The tube foot analog could be actuated with either pneumatic or hydraulic fluid, and could achieve an extended aspect ratio of ca. 6:1.