What do you think this little item could be? It looks like a genie lamp without a lid, doesn't it?
These are invalid feeders, used years ago to feed the sick and feeble that couldn't take nourishment from a spoon. The feeder would be filled with porridge and the bedridden individual could be fed without too much spilling by drinking through the spout.
Most of the invalid feeders I've seen have been white ironstone like the examples in this post. They sell for around $12 to $20 here in Michigan. You might find one in flow blue or with some added decoration that would add value. Last summer a beautiful polychrome (multi-color) transfer ware invalid feeder popped up at an auction I attended. The bidding was quite spirited, and it sold for over $100.