Can someone tell me the difference

[Llg]

Hello. I am a bit confused as to what I have and would like some help. I have these two acans, but they are visibly quite different. The one on the leftt has polyps that are well over 1 inch and I have seen it with long filaments going after my plate coral one night. The other one has about 1 inch polyps with short filaments and doesn't bother the hammer next to it. I just want to figure out what the one on the left is to know what I can really put next to it. Thanks

 

[Nano sapiens]

I have noticed a similar thing regarding these LPS that we call 'Lords' (these are no longer in the Acanthastrea genus, but are now Micromussa lordhowensis).

Two different Lord 'types':

The two orange 'bookends' in this Acan Garden are not only quite a bit larger (1-1/2" vs. 1"), but they also react, and get more of a reaction, from their neighbors than the smaller Lords (my H. bowerbanki have so far only reacted aggressively towards the larger Lords to the point where I had to move them away). These two are also much slower at budding new polyps.

Ultimately, someone in the science field *may* recognize and verify that these are indeed two different species.