Tetragonia / New Zealand spinach / warrigal greens is a reliable self-sower in southeastern Austria. After receiving a generous 14mm (1/2 in.) of rain last night, I could weed today and discovered not only the tetragonia seedlings but also amaranth, echinacea, and tomatoes (not pictured). It's so important to know your seedlings! For comparison: a seed snail of tetragonia, with a random basil in the middle.