You can substitute the similar wood ear mushrooms. Serve these noodles with fresh lime juice and sambal belacan - chilli shrimp paste, which you can either buy (it comes in jars) or make yourself.
Stir in the watercress, then stir in the shrimp and lime juice and season with pepper. Transfer the stir-fry to bowls, sprinkle with the peanuts and serve with rice.
You can buy various types in supermarkets but it's worth seeking out shops that make their own ... serve the rice after mixing in the stir-fried meats, shrimp and mushroom. But it's even better ...