In agreement....however I would lean more towards some sort of glacial involvement.
If you look at the limestone shards they were broken by brute force not thermal action?
Rhyolite doming.
Panum Crater, Mono-Inyo craters is similar in form.
Yep, I’m with you on brute force. Ice could do the breaking, over time. That perfect roundness sure makes a random gas pressure venting or water pushing up the material seem rather miraculous. Just looks to me like something else had to create that channel/borehole. Maybe it’s something that had a number of stages/processes leading to this?
Not only is it perfectly round, it’s level, with the proper amount of material deposited on either side to keep it that way. Pretty amazing! It had to have been pushed up from underneath. Hard to picture broken rock not just sliding down the slope as it’s pushed up. I don’t know, maybe gas could have done it, and the material, broken-up rock from ancient glacier deposits?