There's a moderately popular fruit found in India known as panifal or singada in Hindi. The fruit comes from an aquatic plant that grows in stagnant or slow-moving water up to 10-15 foot deep. Here's what it looks like:
Searching online, I find the fruit has several names in English including water caltrop, water chestnut, buffalo nut, bat nut, devil pod, and ling nut. In China, the name is língjiǎo and in Japan, hishi. I want to know if the fruit is at all known in America. And if so, what's the name it goes by out there?