This is a…

• • spiny anteater
• • horse chestnut
• • sea urchin
• • prickly pear

Spiny anteaters are more formally known as echidnas. They are named after the Greek mythological monster Echidna, who was half woman and half snake. Not coincidentally, echidnas are mammals that resemble reptiles in some respects. They lay eggs and lack nipples, though they do secrete milk through a patch of skin. The platypus is the only other mammal with these attributes. Of course, the platypus has problems of its own, what with the duck’s bill and the poisonous spur in its foot.