Selling Mineral Rights to Universal Royalty Co. Question

Never heard of Universal or Broadmoor but I have gotten several lowball offers from some outfit that calls themselves Addax Minerals operating here in the Barnett. I’m not one of these guys who says that minerals should never be sold, because there are times when it makes sense for an individual to sell versus to hold. In the past, I’ve sold some minerals and have fine experiences with a few companies operating here in the Barnett but this Addax company strikes me as being nefarious. Their ‘landman’ kept telling me that he was ‘in my neighborhood’ seemingly every day, as if he could be at my house at a moment’s notice if I were to decide to accept the less than generous offer that they made me. I also looked at one of their deeds and they try to sneak language in that allows them to collect payments from almost a year in the past before the date that they acquire the rights. Anyway, this Universal offer of 100x monthly cash flow does strike me as unusually high, so either they are highly speculative or they know something that the common man doesn’t know, or they just miscalculated the offer, which has happened to me in the past as well. Not all of these outfits are staffed with rocket scientists. Good luck.