There is another room in Seeding Grounds. It's
kind of hinted at by the same thing that gives away the locations of other secrets in that level, but in a way that's super easy to miss. Anyway, just in case you are one of the people who doesn't find mindlessly hunting for secret walls extremely tedious and tiresome,I'll put the location in secret tags.
Click here to view the secret text
×Find the secret wall leading to it in 3N.
____________________________
Links to neat forum tools that I always have trouble finding:
Click here to view the secret text