See this neat website on bioerosion (http://www.wooster.edu/geology/Bioerosion/Trypanites.html) by a worm like creature called Trypanites. Boring marks are seen quite a bit on horn corals but I rarely find them going through to the septa. This one did but I should have preserved the distal end to see if it was more a rounded or flared.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiMkwwuYkGFVCcMkufIVl4Dq7-TFYaL80Wub_nYnLbaOEMO2xO6XBDE3CjwjaPhxlulP_LEF0V37dBRT1LcPgehDgPzNNcRb2s2-9f2g59-uLEJOss74Ifqrc0yEmY7TaRwShcLGiTMzS7/s400/ordovician-horn-coral.jpg)