havent fought these much so not sure about drop rate. but from the ones in zeruhn mines i recall getting silver ore rather infrequently, but then again a chunk now and then does add up.
They just put what ores you can get from the whole family on every single one. You cannot get them on these worms or i would have my smtihing/gsmithing up quite high.
The ones I found are at I7 and H7 of the second map.
To get there head up to the transition at G6 on the first map then through the short section to to next transition. This is the area, as a level 27, things started to get dangerous so I put on some Silent Oil. I didn't need to be invisible because I saw no more Goblins from that point on.
Then head to the transition at J7, first map. And there your there. I positioned myself in the tunnel between I7 and H7 where you should be safe and have lots of worms nearby.
Even if they are tough, they can be soloed by Black Mages and Rangers.
Anyone know of an area at Shakhrami Maze where you could camp just these without worrying abouot argo from other mobs? I like to kill worms for experience with friends using the ranger and white mage jobs.