Evidence for ET?

[Anomalocaris]

That would be totally different. The sort of “planet” that are believed to form independently of any Star are really miniature star in their own right in terms of composition, just too small to actual ignite or sustain thermal nuclear fussion like normal star.  They are still enormous objects, likely on average much more massive than Jupiter.

I am to understand that matter doesn't conglomerate in progressively larger chunks? That the smallest such accumulated mass would "likely on average much more massive than Jupiter"?

Matter in interstellar medium are only likely to stick together and form sizeable macroscopic chunks if the interstellar medium is already being concentrated by being caught in the gravity well of local over-densities in the interstellar medium. The total mass of local over-density in interstellar medium required to be able to pull additional interstellar material towards itself and concentrate them is many times the mass of Jupiter.

If the process of runaway gravitational collapse is not there to concentrate interstellar matters, then because particles in interstellar medium are extremely far apart and have random motions, the chance of random collision resulting in particles sticking together to form larger particles until the result reach asteroid size is infinitesimal.

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I am to understand that matter doesn't conglomerate in progressively larger chunks? That the smallest such accumulated mass would "likely on average much more massive than Jupiter"?

Jupiter emits twice as much EM as it absorbs from the Sun.  If there were large numbers of Jupiter-sized objects in interstellar spaces (MACHOS), they would have been detected via gravitational lensing, occultations, etc.  Such objects have not been found in large numbers.  Ergo, most large objects form around stars.

Machos suppose a truly enormous numbers of compact planet like objects floating through Milky Way sufficient in total to rival and exceed the mass of all the stars in Milky Way and make up a major portion of the missing matter known to effect milky way’s rotation.

I think that scenario is discredited.

But the notion that Milky Way still has a large number of free floating planets similar in head count to the total number, but not mass, of stars in the Milky Way rather gained support. There have been gravitation lensing events attributed to free floating planets. This does not contradict the notion that most large objects form around stars. Most of the free floating planets could have formed around stars and then subsequently ejected from their system of birth.