This is a clamshell shark, it’s not a hammerhead, lots of people confuse clamshell, scallopshell and hammerhead sharks as the all have that T shape, but there’s physical differences and differences in there pattern of sensing electrical impulses :o)

One bug that irks me is deleting an email on a folder with sorting such as grouped sorting and Thunderbird loses the sorting settings, then I have to reapply the sorting settings again…gah