What type of shower drain is this?

We’ve moved into our new house and are having drainage issues with our shower. Trying to find some information on the type of drain we have as I’ve never seen one like this before. The drain seems to fill and drain over the sides. And there is a round nub at the bottom that sticks up. I have no way of snaking the drain as there is no visible hole. See photo in link. https://ibb.co/3C5TXrb