Natural sponges DO come from the sea. Yes.
But these long scrubber type sponges are actually the skeletons of fruiting vegetables you can grow yourself (and eat mid-summer!)! Here's an old blog post from my family/garden blog that tells all about it. Now is the time to put in your seed order if you want to plant luffa gourds to eat and then save to dry and use as sponges.
If you're going to grow luffas for use as sponges, look for "dishcloth" or "sponge" or "smooth" luffas. They are wider in circumference than the "angled" luffas used in Chinese cuisine. Many seed suppliers have luffa seeds, but my favorite company, Baker Creek Heirloom Seeds, definitely carries a wide variety.
You know those sprouts you find stir-fried in noodle dishes, or maybe raw, by the lime wedges and sriracha sauce next to your bowl of pho? They're VERY nutritious, but don't last more than a couple days in the fridge. However, they ARE easy and fun to sprout yourself. All you need is a small handful of mung beans to produce what you see above. Here are directions for sprouting beans/seeds, posted on my family/gardening blog (directions are also in The Chinese Kitchen Garden book). Try it yourself - sprout your own mung bean, alfalfa, or other seeds and let me know how it goes!
I'm Wendy Kiang-Spray, gardener, home cook, and author of The Chinese Kitchen Garden. Learn more about the book here. Enjoy the blog and be sure to like The Chinese Kitchen Garden Facebook page for notifications when there are new posts.