Please help me identify my cactus :)
It is about 20 years old at about 3 feet tall.
It has 6-7 ribs near the top that fill out towards the middle and bottom.
Here are some more closeup pictures showing the ribs of each arm and how they are more defined at the top and more filled out toward the middle and bottom.
I've tried a few online cactus identification tools, but maybe I'm using the wrong search terms because I can't seem to find anything that quite matches (as far as I can tell).