How do Russian speakers say "like a stump"?

Question

Looking back on a time when we ran into what briefly seemed like a bear in the woods, I wanted to say something in Russian to the effect of our finding ourselves fear-struck and helplessly "riveted to the spot", as we say "like a stump (of a tree)" in English.

In Russian, is it more like:

стоять как столб

than: стоять как пень

I'm also wondering if the usage of "как столб/пень" can extend to instances where you cannot tear/pull yourself away from the TV etc, as if to be rooted in front of them, only because you are completely engrossed in that activity?

Can "как столб/пень" be used to convey the idea of being riveted to the TV screen etc of your own accord, as opposed to fear-induced temporary paralysis? Or in the case of such voluntary immobility, would you use some other expression?

Answer 1

как пень usually refers to sitting, that is сидеть как пень in statements disapproving of lack of activity, e.g.

Сидит целыми днями у телевизора/за компьютером как (тот) пень

как столб is also a disapproving comparison referring to someone else's immovability which creates obstacles

Стал как столб в проходе и ни тебе ни пройти, ни проехать ^{very colloquial}

In this sense как вкопанный (as if dug in) is used as well, but it also fits in the context of having to stop dead in one's tracks because of a startling event or sudden emergence of an obstacle

Меня заворожил протяжный шум лесных верхушек, и я остановился как вкопанный на дорожке

Перед самым барьером конь остановился как вкопанный

In the context of immobile or lifeless laying the comparison is with a log - лежать как бревно

Answer 2

Остолбенеть от ужаса (страха, неожиданности и т. п.). Literally, to become immovable like a pole (столб).

Answer 3

Остолбенеть (to be stunned) is a verb, then there's an idiom «на него столбняк (tetanus) нашел».

For a voluntary action there's «не мог оторваться от телевизора».