Dear  Emmanuel Panteris

In my opinion this image is uninformative. I think even difficult to check if it is the anterior or posterior region of the animal. A full image can help in the determination of the high group. Moreover, is it a terrestrial or aquatic animal?

Best regards

Hudson

The body is not segmented. It may be a nematode.

Dear Huds, 

Your photograph seems like a larvae of Dipteran flies, which bride in small water body.. may be small like flower vase even in very small quantity of water accumulate in any pot. Send me more photograph to proper identify.