Agutaya - they were very small sea urchins, around the size of a golf ball. Also, the guide was the one who actually picked it up, and then he passed it around for us to hold. I saw a few and tried to pick them up myself, but they were wedged in beween a rock pretty good and I was afraid that I would hurt myself or the sea urchin. The spines weren't all that sharp, so as long as we didn't step on them, we didn't need to worry too much about getting poked.
RCCL - Adventure OTS (Honeymoon!)
CCL - Carnival Miracle
RCCL - Enchantment OTS