I just got the game recently and I've seen an enemy a couple times that runs around underground. When you stop they pop out of the ground but when you move they go underground again. They look like teal bags with feet. I can't remember the galaxy where I saw the first one it was really early. But they're also in the gusty garden galaxy on the third star. Underneath the first landmass.
Any pointers or knowledge would be sweet. Thanks.