Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Tournament | Surface | Partner | Opponents | Score |
| --- | --- | --- | --- | --- | --- |
| Winner | Boca Raton , US | Hard | Andrey Kumantsov | Brian Battistone Dann Battistone | 7–5, 6–4 |
| Runner-up | McAllen, Texas , US | Hard | Adam El Mihdawy | Ričardas Berankis Sergey Betov | 3–6, 3–6 |
| Winner | Boca Raton, US | Clay | Tigran Martirosyan | Milan Pokrajac Aleksander Slovic | 6–4, 6–7 (4–7) , [10–7] |
| Runner-up | Kraków , Poland | Clay | Denys Molchanov | Martin Emmrich Hans Podlipnik-Castillo | 4–6, 6–7 (5–7) |
| Runner-up | Glasgow , UK | Hard (i) | Daniel Cox | Chris Eaton Dominic Inglot | 0–6, 6–7 (5–7) |
| Runner-up | Morocco Tennis Tour – Tanger | Clay | Martin Kližan | Steve Darcis Dominik Meffert | 7–5, 5–7, [7–10] |
| Runner-up | Città di Caltanissetta | Clay | Martin Kližan | David Marrero Santiago Ventura | 6–7 (3–7) , 4–6 |
| Winner | Open Prévadiès Saint–Brieuc | Clay (i) | David Marrero | Brian Battistone Ryler DeHeart | 4–6, 6–4, [10–5] |
| Runner-up | Aberto de Bahia | Hard | Martin Kližan | Franco Ferreiro André Sá | 2–6, 4–6 |
| Runner-up | São Paulo , Brazil | Hard | Thomas Fabbiano | Franco Ferreiro André Ghem | 7–6 (7–3) , 4–6, [3–10] |
| Runner-up | Sporting Challenger | Clay | Martin Kližan | Martin Fischer Philipp Oswald | 3–6, 4–6 |
| Winner | Volkswagen Challenger | Carpet (i) | Laurynas Grigelis | Tomasz Bednarek Olivier Charroin | 7–5, 4–6, [10–5] |
| Winner | Challenger La Manche | Hard (i) | Laurynas Grigelis | Dustin Brown Jonathan Marray | 4–6, 7–6 (11–9) , [10–0] |
| Winner | Andijan , Uzbekistan | Hard | Deniss Pavlovs | Vladyslav Manafov Yaraslau Shyla | 6–4, 6–2 |
| Runner-up | Košice Open | Clay | Andrei Vasilevski | Tomasz Bednarek Mateusz Kowalczyk | 6–2, 5–6, [12–14] |
| Winner | Trophée des Alpilles | Hard | Laurynas Grigelis | Jordi Marsé-Vidri Carles Poch-Gradin | 6–7 (4–7) , 6–3, [10–6] |
| Runner-up | IPP Open | Hard | Jimmy Wang | Mikhail Elgin Igor Zelenay | 6–4, 6–7 (0–7) , [4–10] |
Question:
What surface was the città di caltanissetta played on?
Answer:
Clay