Vintage Glass Turnip?

Here's one from my friend, "Tinman."

He says the glass is flawless (smooth, no bubbles, etc.) and in person is a translucent amethyst or pale purple. With lid, the piece is about 8.5" tall and 7.5" in diameter. The lid itself about 3.5" tall. We can't make out the sig. Date reads 1977.

Thanks in advance for any info/comments.