Merge multiple vertices along axis I have been modeling a character only to have blender hiccup during a save while setting up a UV workspace.  Fortunately I was able find an Autosaved version that was relatively recent to I don't have to start Retopology all over.  So I'm marking my seams.  The mirror modifier in the Retopo has been finalized but figured Symmetrize should be fine for copying my seam markings from one side to the other.
Symmetrize seems to have added extra geometry along the X-axis however.  It doesn't go all the way around the model but shows up in sections like shown in the picture.  Is there a relatively simple way to merge multiple sets of Vertices to 0 on the X-axis instead of having to go one group at a time?
There are several addons to make this process fast, but here's a way to do it in plain Blender.
Select all the objects.  Get the 3d cursor where you want them aligned to (perhaps by cursor to selected, perhaps by typing the coordinates into the N panel's View tab 3d cursor section), and set the transform pivot point to 3d cursor - by default I believe that's the . key, though there's a dropdown for it also at the top of the 3d view.
Next, scale the objects with the modal scale operator (s by default), lock the scale to the axis you want to align on, and type 0.  They will all be snapped to the pivot point along that axis.