Noted Torstols
Got 17 noted torstols off those crabs (with RoW), might suggest that these drop items from rare drop table.
other info
uncommon rune claws, gems, and charms to the drop list as well.
weak to stab
aggressive
non-poisonous ( tho the doctor rangers there are poisonous.)
luring the doctors out of the 3 end rooms with doors and then clearing the crabs with melee block prayers/curses best bet.