Tiny Living Organisms Can Interfere With Themselves

Casually reading Do gravitational waves exhibit wave-particle duality?* and during its excellent explanation of waves and how to find them through interference patterns** this pops up:

Even stranger realizations came in the 20th century, as we discovered that:

• Single photons, when you passed them through a double slit one-at-a-time, would still interfere with themselves, producing a pattern consistent with a wave nature.
• Electrons, known to be particles, exhibited this interference and diffraction pattern as well.
• Composite particles, and even tiny living organisms, can interfere with themselves as you pass them through a double slit.
• However, if you measured which slit a photon or electron went through, you wouldn’t get an interference pattern, at all. You will only get one if you don’t make that measurement.

What!? There are tiny living organisms that are both one thing (particles) and another thing (waves). What the!!

* the answer, according to Betteridge's law of headlines is, "No."

** it's very simple really, you've seen it at any pond you've been to.