Aggro: Yes Sound Aggro, drops slime oil rarely, drops horutoto chest key, the chest can be found in various locations through the ruins, this mob spawns in the same room Maltha does, a slightly higher lvl NM that drops a RNG tunic for lvl 16. don't try soloing Maltha if you can't kill blobs somewhat quick.
I solo'd one of these at L18BLM / L4WHM (It /checked as "Decent Challenge") and it nearly killed me. Seemed as though Blizzard was doing slightly more damage than Fire was though but not by much. It could have just been timing issues as it tended to hit me the same time as I'd cast Blizzard, so it would get damage from my Blaze Spikes as well.
The key is used for in a chest deep in the Inner Ruins...I fought the blob in close proximity of A large door. To get to the location of the chest go to East Sartaburata J-7 to enter in the Inner Ruins. At G-8 of the ruins look for a cracked wall action it to open. Then head down to F-9 there you will find the chest.