It is possible you have found a multi-cellular life form. How exciting! The process of ingestion (eating) that it employs may not be as obvious as the "bulb" seen under the microscope, but it could be similar. The bubbles, I believe, are waste gases produced by its biologic process.

I am curious about the fact that the bubbles are not distributed uniformly. However, the entity itself appears to vary in size and shape, so that may easily explain the fact that different parts produce different amounts of bubbles.

The area above the opening you found has a large concentration of bubbles. I do find it interesting that the bubbles "congregate" directly beneath it. I am not willing to suggest an intelligence behind that, but I do suspect it is not entirely accidental.

Please continue your investigations.

Your friend, Koala