Here is a Luffa cylindra 'sponge' AKA Loofa that I harvested and peeled recently. The first time I grew luffa many years ago I was told I should wait until the outside of the Luffa turned dark brown before harvested them. That worked for me the first time I grew them, but not with last years crop. Some of the Luffa gourds from last year that I was waiting on to turn brown actually kind of disintegrated inside from the excessive Florida summer humidity. This year I have been harvesting the gourds just when they turn this beautiful ripened yellow color. The peel comes off easily by hand at this stage. The 'sponge' is kind of soft coming out of the peel. If you let it dry out and harden for a couple of days, then you can get the seeds out by hitting it on a hard surface and shaking the seeds out. Some people suggest to wash out the gourds right after harvest, but they are very clean coming right out of the peel. I haven't cleaned them out that way, because I wanted the seeds to dry in good condition for seed saving.Fair Share.
Would you like some seeds for yourself? I have Luffa seed free with purchase in my etsy shop.