Shop › Lava Tube Black Short Sleeve Tee Image 1 of 1 Lava Tube Black Short Sleeve Tee from $25.00 Featuring Walter the mule and his favorite palm tree, this comfy cotton-poly blend is perfect for snorkeling or spelunking. Size: Select Size Small Medium Large Extra Large XXLarge Add To Cart Added! Featuring Walter the mule and his favorite palm tree, this comfy cotton-poly blend is perfect for snorkeling or spelunking.