Not a limpet, this has two halves, outside starts as red then transitions to green at the baseHard to see on my cell phone but possibly a limpet?
While it is not this exact one it does appear to be a mussel of some sort. Thankyou for some insight as to what it isMy reply is not because of your picture, because I can't see anything, but that might be because I'm colorblind.....but my reply is from your red/green comment. There is an invasive mussel from Asia commonly known as the green mussel. When young, they are brightly red/green, and what I've seen is red at the base and more green at the lip.....opposite to what you've said. As they turn into adults, the colors fade. But again, that's the best I can do for a guess....google search Green Mussel and see if that's what you have.
So the question remains- do you keep it, or toss it. I don't know what I'd do- I like different stuff- sometimes I take chances- I got a couple of differnt kinds of sponges- pineapples are fine the 'roots' are a pain- I had/ maybe still have a nudibanch of some kind , and recently found a brittle star, which lost some of it's legs when I moved it from one tank to anotherWhile it is not this exact one it does appear to be a mussel of some sort. Thankyou for some insight as to what it is
Leave it be.So the question remains- do you keep it, or toss it. I don't know what I'd do- I like different stuff- sometimes I take chances- I got a couple of differnt kinds of sponges- pineapples are fine the 'roots' are a pain- I had/ maybe still have a nudibanch of some kind , and recently found a brittle star, which lost some of it's legs when I moved it from one tank to another