I'm a solid, unaffected by newtonian gravity.

The next user is a small piece of INSL that has caught fire, because INSL is absolutely flammable. You might be thinking of BTRY.

I'm one pixel of deut with life 0 (<offtopic>gives meaning to having no life, lol</offtopic>), so it passes through me unharmed.

The next user is penetrated by millions of protons with temp 9725.85 C (which means you cannot block it, as they are passing through you already).

I become LAVA. As a simulated particle, I don't really care. By the way, DMND can't be penetrated by PROT...

The next user is a NEUT that goes over the edge of the screen and is deleted from memory.

... With a water gun.

The next user isn't pro enough.