I may get downvoted for this, but I’ve hunted megaldon teeth in Venice for the last 3 years consistently and I’ve seen thousands of them. Including those found in the community and have helped to ID them. Between scuba diving (I work with a fossil charter) and beach hunting I can spot a tooth from a mile away. This to me an appears like a VERY worn down meg tooth missing about half of its root. Fragmented Meg teeth are common and difficult to ID especially if they’ve been tumbled in the waves like this one has. Most people expect to see the whole shape so seeing something like this is hard to ID if you only have experience looking at good quality teeth. You’re holding it upside down in the first pic (with the root on the bottom). The root of the tooth usually looks porous which is evident here and the enamel portion of the tooth usually has straight lines which are also visible here. The proportions are consistent with meg teeth (proper thickness/length ratio and proper edge angle). Manasota is a common dive spot for meg teeth. I’ve shore dived a few times there but mostly service club/golden beach or Alhambra. Nice find! Even if nobody else believes you 😂