I think you were asking about Tua Tua’s somewhere. They would be good bait.
You go down to the very end of Rocking Horse Rd (Southshore Spit). Go out to the beach at low tide and look for areas of green weed on the surface which looks like it’s stuck to the sand. Dig right there and typically you’ll find Tua Tua’s. One year I found hardly any for some unknown reason but apart from that I’ve always found them.
I’ve never really seen the at New Brighton Beach. There might be beds of Tua Tua at certain areas but I used to live down the end of Southshore and that’s where I always found them.