You can easily die if they grab you from behind and you can also get grabbed while facing them (but you can survive with very little HP)
Those things they drop aren't actually 'Pebbles.' They are petrified eyes. Which makes sense because the are called 'Eye Collectors,' drop Bloodshot Eyeballs, & that the item image of the 'Pebbles' more resemble eyes.
Looks like her and even scream like her...wow...talk about flashbacks to Safeways deli! Lol! Fire also takes them out fast,