But note that Tolkien had at least one "tentacled blob" in Lord of the Rings (the Watcher in the Water), and he introduced it ... and later the Balrog ... in very Lovecraftian terms. So Lovecraftian that I'm pretty sure he'd read some of the Mythos stories.

And remember that even Morgoth was intimidated by Ungoliant? Tolkien really did not like spiders ... wonder if he'd ever heard of Clark Ashton Smith's Atlach-Nacha?