This morning I decided to check out my tank with the moonlight on and saw this thing attached to my rock. I thought it was my shrimp molt. I used the turkey baster to try and suck up the molt but it was stuck on there pretty good. I realized it wasn’t a molt, after I got it out after a few attempts I noticed it left a perfect round hole in that spot. I check over the rest of the rock and there were a few more spots with the same exact perfectly round hole. Can anyone help explain this? TIA