Hard to mistake Trachelius for anything else when you see it.
While the top shot might look as if the specimen is being flattened by the coverslip, that is not the case. These large ciliates are shaped like big rounded balloons, and this is the way they appear when you are focused "into" the cell. The second shot is a close view of the proboscis. You can observe the synchronized movement of the cilia
Images made through a microscope. All subject types.