What egg-laying mammal has a venomous spur?

The platypus is the egg-laying mammal with a venomous spur.

The platypus (Ornithorhynchus anatinus) is a semiaquatic monotreme native to eastern Australia, including Tasmania. Like echidnas, it lays eggs rather than giving birth to live young, making it one of only five living monotreme species.

Adult male platypuses retain a sharp spur on each hind foot. The spurs connect to crural glands that produce venom, especially during the breeding season. The venom can cause extreme, long-lasting pain and swelling in humans, although it is not normally fatal. Scientists believe males primarily use it in conflicts with rivals.

A common mix-up is echidnas: female and male echidnas develop spur buds, but echidnas do not have functional venom glands. The platypus is also unusual because females nurse their young without nipples; milk is released through skin pores and lapped from the fur.