Is it common for these guy to end up upside down? I got 2 zebra and one tiger nerite snail, they are alive. Once I put them in tank I saw one upside down trying to right himself. I didn’t wait to see if he could, I helped him by putting him near glass and he attached. A few hours later the other one was upside down. Do these guys need to be on glass in order to not fall? I have sand substrate. Also, do I need to attach algae Wafers to glass?