Flotsam ooze drop flotsam jelly (used to make elemental potion of locate object)
Currently these only spawn in the shallow and middle layers of the elemental plain of water.
With the nerf to the loot torch, these potions might be more useful, and worth farming.
Unfortunately right now, you have to shackle and farm on the shallow and middle layers. If the spawns of flotsam ooze were in the deep layer, you could do both the elemental plains bosses and get some potions at the same time, making elemental plains more appealing