The two major reasons I don't think it's a LTA:
1. They usually don't do very well. Although your tank water may be perfect, lighting perfect, still, they typically move around a lot until they end up in your powerhead. If you can keep them out of the powerhead long enough for them to settle and begin to do well, they don't typically grow this fast. (Although I'm sure there are exceptions)
2. It's blown up on top of the rockwork. LTA's like to bury their columns in either the sand or between rocks..again, *typically*