Download Echidna Egg Laying Mammals PNG. Platypus and echidna are very strange animals, probably the strangest animals on earth. See more ideas about egg laying mammals, mammals, echidna. The spines, which reach 50 mm in length, are in fact modified hairs. The echidna is quite unique as it's a mammal that lays eggs rather than giving birth to live young. This ability has fascinated biologists and study into the area the platypus and echidna are the only two mammal species which can lay eggs. The echidna is a type of mammal that lays eggs. They lay eggs but produce milk and that's what they feed their young on. Echidna is as strange as platypus. Echidna and platypus are belong to the group prothatic.An echidna is mammal that lays eggs.